Breast Cancer Glossary

A

Absolute Risk
A person’s chance of developing a certain disease over a certain period of time. The absolute risk of a disease is estimated by looking at a large group of people who are similar in some way (the same age, for example) and counting the number of people in this group who develop the disease over a certain period of time. For example, if we followed 100,000 women between the ages of 30 and 34 for one year, about 29 would develop breast cancer. This means the one-year absolute risk of breast cancer for a 30- to 34-year-old woman is 29 per 100,000 women (about 1 per 3,450 women).

Acupuncture
Use of very thin needles inserted at precise points on the body. It may help control pain and other side effects of breast cancer treatment or the cancer itself. It is a type of complementary or integrative therapy.

Adjuvant (Systemic) Therapy
Treatment given in addition to surgery and radiation therapy to get rid of breast cancer cells that may have spread from the breast to other parts of the body. It may include chemotherapy, hormone therapy and/or HER2-targeted therapy.

Advocacy (see Breast Cancer Advocacy)

Aesthetic Flat Closure
Surgery done after a mastectomy to create a smooth chest wall that appears flat. Extra skin, fat and other tissue in the breast area may be removed. This surgery is an option for people who wish to “go flat” after a mastectomy. It may also be done if a breast implant is removed (an implant that was part of breast reconstruction after a mastectomy).

Alopecia
Hair loss.

Alternative Therapy
Any therapy used instead of standard medical treatments such as surgery, chemotherapy and hormone therapy. Alternative therapies are different from complementary and integrative therapies, which are used in addition to standard treatments. Alternative therapies have not been shown to be effective in treating breast cancer, so it’s not safe to use them.

Amenorrhea
The absence or stopping of menstrual periods. 

Anesthesia
Loss of feeling or sensation that keeps a person from feeling pain during surgery or other medical procedures. Local or regional anesthesia may be used for a specific part of the body, such as the breast, by injection of a drug into the area. General anesthesia numbs the entire body and puts a person to sleep with drugs that are inhaled or injected into a vein.

Aneuploid (DNA Ploidy)
The presence of an abnormal number of chromosomes in cancer cells.

Angiogenesis
The growth of new blood vessels that cells need to grow.  

Antibody
A protein made by white blood cells that’s part of the body’s immune system. Each antibody binds to a certain antigen (foreign substance, such as bacteria) and helps the body fight the antigen.

Antibody-Drug Conjugate
A combination of a HER2-targeted antibody drug and a chemotherapy drug. The combination allows the targeted delivery of chemotherapy to certain cancer cells. Ado-trastuzumab emtansine (Kadcyla, T-DM1, trastuzumab emtansine) is an example of an antibody-drug conjugate used to treat breast cancer.

Antibody Therapy
A drug containing an antibody specially made to target certain cancer cells. See Antibody.

Anti-Carcinogen
An agent that counteracts carcinogens (things that cause cancer).

Antiemetic
A medicine that prevents or relieves nausea and vomiting.

Antigen
A substance that causes an immune response in the body. This immune response often involves making antibodies.

Antioxidant
A substance that protects the body against damage from oxidizing agents. Oxidizing agents are always present in the body and are often beneficial. However, when large amounts of oxidants are present in cells, they can cause damage, especially to DNA. This can lead to abnormal cell growth. Antioxidants include beta-carotene, vitamin A, vitamin C and vitamin E.

Apoptosis
A normal cell process that leads to the death of a cell. Cancer cells may block apoptosis.

Architectural Distortion
A finding on a mammogram that describes an abnormal (distorted) shape or pattern of breast tissue, but no mass is seen. Although the breast tissue may be normal, this finding usually needs follow-up testing because it may be a sign of a benign (not cancer) breast condition or breast cancer.

Areola
The darkly shaded circle of skin around the nipple.

Aromatase Inhibitors
Hormone therapy drugs that lower estrogen levels in the body by blocking aromatase, an enzyme that converts other hormones into estrogen. Aromatase inhibitors are used to treat hormone-receptor positive breast cancer.

Aspirate
To remove fluid and a small number of cells.

Atrophic Vaginitis (see Vaginal Atrophy)

Atypical Hyperplasia
A benign (not cancer) breast condition where breast cells are growing rapidly (proliferating). The proliferating cells look abnormal under a microscope. Although atypical hyperplasia is not breast cancer, it increases the risk of breast cancer.

Autologous
A blood donation or tissue graft from a person’s own body rather than from another person (a donor). For example, autologous breast reconstruction techniques use skin and tissue flaps (grafts) from a person’s own body.

Axilla
The underarm area.

Axillary Dissection (Axillary Sampling)
Surgical procedure to remove some or all of the lymph nodes from the underarm area so the nodes can be examined under a microscope to check whether cancer cells are present.

Axillary Lymph Nodes
The lymph nodes in the underarm area.

Ayurveda
A complementary or integrative medical system from India that involves diet, exercise, meditation and massage. Ayurveda means “life-knowledge.”

B

Benign
Not cancerous. Does not invade nearby tissue or spread to other parts of the body.

Benign Breast Conditions (Benign Breast Disease)
Noncancerous conditions of the breast that can result in lumps or other abnormalities. Examples include cysts and fibroadenomas.

Benign Phyllodes Tumor
A rare benign (not cancer) breast condition similar to a fibroadenoma. A lump may be felt, but is usually painless.  

Bilateral Prophylactic Mastectomy
Surgery where both breasts are removed to prevent breast cancer from developing.

Biobank (Tissue Repository)
A large collection of tissue samples and medical data used for research studies.

Bioimpedance (Bioelectrical Impedance Analysis)
A method of measuring the amount of fluid in body tissues.

Biological Therapy
A therapy that targets something specific to the biology of a cancer cell, as opposed to chemotherapy, which attacks all rapidly dividing cells. Often used to describe therapies that use the immune system to fight cancer (immunotherapy).

Biomarker
Any molecule in your body that can be measured and can give information about your health.

Biopsy
Removal of tissue to be tested for cancer cells.

Biosimilars 
“Generic-like” versions of drugs containing biological products (such as antibodies) used for a variety of conditions and diseases, like breast cancer.

Bisphosphonates
Bone density medications used to help prevent bone loss (osteoporosis). These drugs can be used to lower the risk of breast cancer recurrence in some women with early breast cancer. They are also used to strengthen bones and decrease the rate of bone fractures and pain due to breast cancer metastases to the bone.

Body Mass Index (BMI)
A measure used to estimate body fat. BMI takes into account a person’s height and weight. Calculate your BMI.

Bone Scan
A test done to check for signs of cancer in the bones. A small amount of radioactive material is injected into the bloodstream. It collects in the bones, especially abnormal areas, and is detected by a scanner. Bone scans can show cancer as well as benign bone diseases (like arthritis).

Boost
Additional dose of radiation to the part of the breast that had the tumor.

BRCA1 and BRCA2 Genes (BReast CAncer genes)
Genes that help limit cell growth. A mutation (change) in one of these genes increases a person’s risk of breast, ovarian and certain other cancers.

Brachytherapy
A procedure that uses targeted radiation therapy from inside the tumor bed.

Breast Cancer
An uncontrolled growth of abnormal breast cells. 

Breast Cancer Advocacy
Influencing targeted audiences to promote the support of breast cancer issues.

Breast Cancer Survivor (see Survivor)

Breast Conserving Surgery (see Lumpectomy)  

Breast Density
A measure used to describe the relative amounts of fat and tissue in the breasts as seen on a mammogram.

Breast-Specific Gamma Imaging (see Molecular Breast Imaging)

Breast hamartoma
A very rare benign (not cancer) breast condition made up of cells and tissue normally found in the breast.

Breast Imaging Reporting and Data System (BI-RADS^®)
A system developed by the American College of Radiology to provide a standard way to describe findings on a mammogram.

Breast Reconstruction
Surgery to restore the look and feel of the breast after mastectomy.

Breast Self-Examination (BSE)
A method that may help some women become familiar with the normal look and feel of their breasts. BSE is not recommended as a breast cancer screening tool because it has not been shown to decrease breast cancer death.

Breast Tomosynthesis (3D Digital Mammography, Digital Tomosynthesis)
A tool that uses a digital mammography machine to take multiple 2-dimensional (2D) X-ray images of the breast. Computer software combines the multiple 2D images into a 3-dimensional (3D) image.

C

Cachexia
Loss of appetite and weight. 

Calcifications
Deposits of calcium in the breast that appear as bright, white spots on a mammogram. Most calcifications are not cancer. However, tight clusters or lines of tiny calcifications (called microcalcifications) can be a sign of breast cancer.

Cancer
General name for over 100 diseases with uncontrolled cell growth.

Cancer Rehabilitation
Programs that help people with cancer improve their quality of life by regaining physical strength and emotional well-being during and after cancer treatment. These programs help people stay active in their home and work lives and may include exercise, nutrition counseling and pain management.

Cancer Staging (see Staging) 

Carcinoma in Situ (in Situ Carcinoma)
Condition where abnormal cells are found in the milk ducts or lobules of the breast, but not in the surrounding breast tissue. In situ means “in place.” See ductal carcinoma in situ and lobular carcinoma in situ.

Case-Control Study
An observational study that looks at 2 groups–one with people who already have the outcome of interest (cases), and one with people who do not (controls). For example, the cases may be women with breast cancer and the controls may be women who do not have breast cancer. The 2 groups are compared to see if any factor was more common in the past history of one group compared to the other.

Case Series
A health care provider’s observations of a group of patients who are given a certain type of treatment.

Catheter
A small tube used to deliver fluids to (or remove them from) the body.

CDK4/6 Inhibitors
A class of drugs designed to interrupt the growth of cancer cells by blocking the enzymes CDK4 and CDK6 (important in cell division). Abemaciclib (Verzenio) is an example of a CDK4/6 inhibitor used to treat breast cancer.

Centigray (Centigrays)
One centigray describes the amount of radiation absorbed by the body and is equivalent to 1 RAD (radiation absorbed dose).

Checkpoint Inhibitor
A type of immunotherapy drug that “takes the brakes off” the natural factors that limit how the immune system can control cancer cells. Pembrolizumab (Keytruda) is an example of a checkpoint inhibitor immunotherapy drug used to treat breast cancer.

Chemoprevention (Risk-Lowering Drugs)
A drug or combination of drugs used to lower the risk of breast cancer in women who do not have breast cancer, but are at higher risk.

Chemotherapy
A drug or combination of drugs that kills cancer cells.

Clinical Breast Examination (CBE)
A physical exam done by a health care provider to check the look and feel of the breasts and underarm for any changes or abnormalities (such as lumps).

Clinical Trials
Research studies that test the benefits of possible new ways to detect, diagnose, treat or prevent disease. People volunteer to take part in these studies.

Cognitive Function
Mental processes related to understanding, such as reasoning and problem-solving.

Cohort Study
A study that follows a large group of people (a cohort) over time.

Co-Insurance (see Co-Payment)  

Complementary Therapies (Integrative Therapies)
Therapies (such as acupuncture or massage) used in addition to standard medical treatments. Complementary therapies are not used to treat cancer, but they may help improve quality of life and relieve some side effects of treatment or the cancer itself. When complementary therapies are combined with standard medical care, they are often called integrative therapies.

Complex Cyst
A fluid-filled sac. A breast ultrasound finds the cyst has thick walls and contains some solid matter. A biopsy is needed to confirm that a complex cyst is benign (not cancer).

Complicated Cyst
A fluid-filled sac. A breast ultrasound finds small echoes in the cyst, but the cyst only contains fluid. A biopsy may be done to confirm a complicated cyst is benign (not cancer).

Computer-Assisted Detection (CAD)
Software developed to help radiologists find suspicious areas on a mammogram.

Computerized Axial Tomography (CAT) Scan (see CT Scan)

95% Confidence Interval (95% CI)
A statistical concept that shows there is a 95 percent probability the true measure is found within a range of measures computed from a single study. For example, if the 95% confidence interval for a survival rate is 75 to 90 percent, there is a 95 percent chance the true survival rate falls between 75 and 90 percent.  

Co-Payment (Co-Insurance)
In an insurance plan, the portion of medical costs a person must pay (the portion not covered by his/her insurance policy).

Cording
A condition that may occur after surgery to the lymph nodes in the underarm area (axillary nodes). The lymph vessels that had been connected to the removed lymph nodes become tight and the tissue can thicken and look like cords under the skin. Cording can be treated.

Core Needle Biopsy
A needle biopsy that uses a hollow needle to remove samples of tissue from an abnormal area in the breast.

Co-Survivor
A person who gives support to someone diagnosed with breast cancer, from the time of diagnosis through treatment and beyond. Co-survivors may include family members, spouses or partners, friends, health care providers and colleagues. 

CT Scan (Computerized Tomography Scan, Computerized Axial Tomography (CAT) Scan)
A series of pictures created by a computer linked to an X-ray machine. The scan gives detailed internal images of the body.

Cumulative Risk
The sum of a person’s chances of developing a disease (such as breast cancer) over the course of a lifetime. For example, the cumulative (lifetime) risk of breast cancer for women is about 1 in 8 (or about 12 percent). This means for every 8 women, one will be diagnosed with breast cancer during her lifetime.

Cyst
A fluid-filled sac. See Simple Cyst, Complicated Cyst and Complex Cyst.

Cytopathologist
A pathologist who specializes in looking at individual cells. A cytopathologist is needed to interpret the results of a fine needle aspiration (fine needle biopsy).

Cytotoxic
Toxic, or deadly, to cells. Often used to describe chemotherapy.

D

De Novo Metastatic Breast Cancer
Breast cancer that is metastatic (stage IV) when it’s first diagnosed.

Deductible (Insurance Deductible)
The pre-set amount of medical costs a person must pay before insurance payments begin.

Definitive Surgery
All of the known tumor is removed and no follow-up surgery is needed.

Diabetic Mastopathy
A rare benign (not cancer) breast condition that consists of small, hard masses in the breast. It occurs most often in women with insulin-dependent (type 1) diabetes.

Diagnosis
Identification of a disease from its signs and symptoms.

Diagnostic Mammogram
A mammogram used to check symptoms of breast cancer (such as a lump) or an abnormal finding on a screening mammogram or clinical breast exam. It involves 2 or more views of the breast.

Diagnostic Radiologist (Radiologist)
A health care provider who specializes in the diagnosis of diseases using X-rays.

Diploid (DNA Ploidy)
The presence of a normal number of chromosomes in cancer cells.

Disease-Free Survival Rate
Percent of people alive and without disease at a certain time (often 5 years or 10 years) after treatment. Those who die from causes other than the disease under study are not included in this measure.

Distant Recurrence (see Metastases)

Distress
Emotional, spiritual or physical pain or other suffering that may cause sadness, fear, depression, anxiety or loneliness.

DNA (Deoxyribonucleic Acid)
The information contained in a gene.

Dose-Dense Therapy
Chemotherapy given over a shorter (more condensed) time period compared to standard therapy. The frequency of treatment sessions is increased, so the length of the treatment period is shortened.

Down-Staging
Lowering the stage of a cancer from its original stage (or the stage it was thought to be). Down-staging occurs most often after a good response to neoadjuvant therapy. Neoadjuvant therapy is chemotherapy or hormone therapy used as a first treatment (before surgery). Neoadjuvant therapy can shrink a tumor enough that it lowers the stage of the breast cancer and a lumpectomy, instead of a mastectomy, can be done.  

Duct (Milk Duct, Mammary Duct)
A canal that carries milk from the lobules to a nipple opening during breastfeeding (see figure). 

Ductal Carcinoma in Situ (DCIS, Intraductal Carcinoma)
A non-invasive breast cancer that begins in the milk ducts of the breast, but has not invaded nearby breast tissue. Also called stage 0 or pre-invasive breast carcinoma.

Ductal Papilloma (see Intraductal Papilloma)

E

Early Breast Cancer 
Cancer that is contained in the breast or has only spread to lymph nodes in the underarm area. This term often describes stage I and stage II breast cancer.

Edema
Excess fluid in body tissues that causes swelling.

Endocrine Therapy (see Hormone Therapy)

Endometrial Cancer
Cancer of the endometrium (the lining of the uterus).

Enzyme
A protein that speeds up biologic reactions in the body.

Epidemiology
The study of the causes and prevention of disease.

Estradiol
The most biologically active, naturally-occurring estrogen in women.

Estrogen
A female hormone produced by the ovaries and adrenal glands that’s important to reproduction. Some cancers need estrogen to grow.

Estrogen Receptors
Special proteins in cells that estrogen hormones attach to. A high number of estrogen receptors in a breast cancer cell often means the cancer cell needs estrogen to grow.

Etiology
The cause(s) of a disease.

Excisional Biopsy
Surgical procedure that removes the entire abnormal area (plus some surrounding normal tissue) from the breast.

External Beam Radiation Therapy (see Radiation Therapy)

F

False Negative
A test result that incorrectly reports a person is disease-free when she/he actually has the disease.

False Positive
A test result that incorrectly reports a person has a disease when she/he does not have the disease.

Family History (Family Medical History)
A record of the current and past health conditions of a person’s biological (blood-related) family members that may help show patterns of diseases within a family.

Fat Necrosis
A benign (not cancer) breast change in which the breast responds to trauma with a firm, irregular mass, often years after the event. The mass is the result of fatty tissue dying, after either surgery or blunt trauma to the breast. This breast change does not increase risk of breast cancer.

FDA Approval (of a drug)
The process the U.S. Food and Drug Administration (FDA) uses to determine whether a drug’s benefits outweigh its known and potential risks. If a drug is FDA-approved, it means the FDA has reviewed the data on the drug’s effects and determined the drug will benefit the people intended to use the drug. Often, but not always, for cancer drugs, a drug needs to perform better than standard therapy to be FDA-approved.

FDA Accelerated Approval (of a drug)
In some cases, when there are promising early data on a drug for a serious medical condition, the U.S. Food and Drug Administration (FDA) gives a drug a short-term approval. This is called Accelerated Approval. Researchers may not yet have data on standard outcomes, such as survival. However, given the available data, the FDA determines the predicted benefits of the drug outweigh its known and potential risks. If further data confirm the predicted benefit, the drug is given full FDA approval. If further data fail to show the predicted benefit, the FDA may withdraw approval.

Fibroadenoma
A benign (not cancer) fibrous tumor that may occur at any age, but is more common in young adulthood.

Fibrocystic Condition (Fibrocystic Changes)
A general term used to describe a benign (not cancer) breast condition that may cause painful cysts or lumpy breasts.

Financial Toxicity (Financial Burden)
The economic hardship and distress caused by high medical care costs.

Fine Needle Aspiration (FNA, Fine Needle Biopsy)
A biopsy procedure that uses a thin, hollow needle to remove a sample of cells from the abnormal area of the breast.

First-Degree Relative (Immediate Family Member)
A person’s mother, father, sister, brother or child.

First-Line Therapy
The initial (first) therapy used in a person’s cancer treatment.

Flow Cytometry
A laboratory test done on tumor tissue to measure the growth rate of the cancer cells and to check if the cells have too much DNA.

Fluorescence In Situ Hybridization (FISH)
A laboratory test done on breast tumor tissue to find out the number of copies of the HER2 gene contained in the cancer cells.

Frozen Section
Process where a portion of tissue from a surgical biopsy is frozen so a thin slice can be studied to check for cancer. Frozen section results are only preliminary and always need to be confirmed by other methods.

G

Gail Model (Breast Cancer Risk Assessment Tool)
A tool that uses personal and family breast cancer history as well as other factors to estimate a woman’s risk of invasive breast cancer.

Galactocele
A milk-filled cyst.

Galactorrhea
Milky nipple discharge not related to breastfeeding.

Genes
The part of a cell that contains DNA. The DNA information in a person’s genes is inherited from both sides of a person’s family (you get half of your genes from your mother and half from your father).

Gene Expression
Process in which a gene gets turned on in a cell to make RNA and proteins.

Gene Expression Profiling (see Tumor Profiling)

Gene Mutation
Any change in the DNA (the information contained in a gene) of a cell. Gene mutations can be harmful, beneficial or have no effect.

Gene Variant of Uncertain Significance
A gene mutation not currently known to increase breast cancer risk.

General Practitioner (Internist, Physician)
Personal or family physician.

Generic
The chemical name of a drug, not the brand name. The chemical formulas of a generic drug and the brand name drug are the same.  

Genetic (Hereditary)
Related to genes. The information in a person’s genes can be passed on (inherited) from either parent.

Genetic Counseling
A discussion between a genetic counselor or other trained health professional and a person concerned about inherited gene mutations related to health risks. The person’s personal and family health history are discussed. Genetic counseling helps determine whether or not genetic testing is appropriate. The risks and benefits of genetic testing are also discussed.

Genetic Susceptibility (Genetic Predisposition)
An increased likelihood or chance of developing a disease due to specific changes in a person’s genes passed on from either parent.

Genetic Testing (Germline Testing)
Analyzing DNA to look for an inherited gene mutation in a person that may show an increased risk for developing a specific disease.

Genome
The total genetic information of an organism.

Genomic testing
Analyzing DNA to check for gene mutations. Some use genomic testing to refer to genetic testing, which tests the DNA of a person. Others use it to refer to tumor profiling (gene expression profiling), which tests the DNA of a cancer. 

Genomics
The study of genes and their functions.

Germline Mutation
An inherited change in the genetic code of a person that affects the function of a gene. Germline mutations can be passed on from parents to children (you get half of your genes from your mother and half from your father). Also called inherited gene mutation.

Germline Testing (see Genetic Testing)

Glandular Tissue (in the breast)
The tissue in the breast that includes the milk ducts and lobules. 

Grade (see Tumor Grade)

Guaranteed Renewable Insurance
A health insurance policy that requires the insurance company to renew your policy for a certain amount of time, even if your health condition changes.

H

H&E (Hematoxylin and Eosin) Staining
A laboratory test that gives color to cells so cell structures can be identified.

HER2 (Human Epidermal Growth Factor Receptor 2, HER2/neu, erbB2)
A protein involved in cell growth and survival that appears on the surface of some breast cancer cells. HER2-negative breast cancers have little or no HER2 protein. HER2-positive breast cancers have a lot of HER2 protein. HER2-positive tumors can be treated with HER2-targeted therapies, such as trastuzumab (Herceptin). 

HER2-Low Metastatic Breast Cancer
Metastatic breast cancers with tumor cells that have low, but detectable levels of HER2 expression (defined by an immunohistochemistry (IHC) score of 1+ or 2+).

HER2-Targeted Therapies
Drugs designed to target and treat HER2-positive breast cancers. The breast cancers have a lot of HER2 protein on the surface of their cells. Trastuzumab (Herceptin) is an example of a HER2-targeted therapy.

Hereditary (see Genetic)

Homeopathy (Homeopathic Medicine)
A medical system based on a belief that “like cures like.” Natural substances are specially prepared in small amounts to restore health. These substances cause symptoms similar to the condition they are meant to treat in healthy people. There are limited data on the safety of these substances.

Hormones
Chemicals made by certain glands and tissues in the body, often in response to signals from the pituitary gland or the adrenal gland. Hormones have specific effects on specific target organs and tissues. Examples include estrogen and progesterone. Hormones can also be made in a lab.

Hormone Receptors
Specific proteins in cells that hormones attach to. A high number of hormone receptors on a breast cancer cell often means the cancer cell needs the hormone to grow.

Hormone Receptor Status
Shows whether or not a breast cancer needs hormones to grow. A hormone receptor-positive (estrogen and/or progesterone receptor-positive) cancer needs hormones to grow. A hormone receptor-negative (estrogen and/or progesterone receptor-negative) cancer does not need hormones to grow. See Hormone Receptor.

Hormone Replacement Therapy (see Menopausal Hormone Therapy)  

Hormone Therapy (Endocrine Therapy)
Treatment that works by keeping cancer cells with hormone receptors from getting the hormones they need to grow.

Hospice
A philosophy of care focusing on improving quality of life and easing pain and other symptoms at the end stage of a terminal illness. Hospice care also provides support services to patients and their families.

Hyperplasia (Usual and Atypical Hyperplasia)
A benign (not cancer) breast condition where breast cells are growing rapidly (proliferating). Although hyperplasia is not breast cancer, it increases the risk of breast cancer. In usual hyperplasia, the proliferating cells look normal under a microscope. In atypical hyperplasia, the proliferating cells look abnormal.

I

Immediate Family Member (First-Degree Relative)
A person’s mother, father, sister, brother or child.

Immunotherapy
Therapies that use the immune system to fight cancer. These therapies target something specific to the biology of the cancer cell, as opposed to chemotherapy, which attacks all rapidly dividing cells. Pembrolizumab (Keytruda) is an example of a checkpoint inhibitor immunotherapy drug used to treat breast cancer.

Immunohistochemistry (IHC)
A lab test done on tumor tissue to detect the amount of HER2 protein on the surface of the cancer cells.

Implant (Breast Implant)
An “envelope” containing silicone, saline or both, that is used to restore the breast form after a mastectomy (or for other cosmetic reasons).

In Situ Carcinoma (see Carcinoma in Situ)

In-Network Provider
The health care providers and medical centers (hospitals and other treatment centers) that are part of a group health plan or health maintenance organization (HMO).

Incidence
The number of new cases of a disease that develop in a specific time period.

Incisional Biopsy
Surgical biopsy that removes only part of the tumor.

Indemnity Policy
A prepayment insurance plan that gives services or a cash payment for medical care needed in times of illness or disability.

Induction Chemotherapy (see Neoadjuvant Chemotherapy)

Inflammatory Breast Cancer (IBC)
A rare, aggressive form of invasive breast cancer. Its main symptoms are swelling (inflammation) and redness of the breast. The skin on the breast may look dimpled, like the skin of an orange, and may be warm to the touch.

Informed Consent
The process through which a person learns about the possible benefits and risks (including side effects) of a treatment plan and then accepts or declines the treatment. The person is usually asked to sign a consent form, but may stop the treatment at any time and get other medical care.

Infraclavicular Lymph Nodes
The lymph nodes below the clavicle (collarbone). See Lymph Nodes.

Insurance Payment Cap
A maximum amount an insurance company will pay out in a given time period.

Insurance Premium (Premium)
The cost of insurance coverage for a certain period of time.

Integrative Therapies (see Complementary Therapies)

Intraductal
Within the milk duct. Intraductal can describe a benign (not cancer) or malignant (cancerous) process.

Intraductal Hyperplasia
An excess of cells growing within the milk ducts of the breast. 

Intraductal Papilloma (Ductal Papilloma)
Small, benign (not cancer) growths that begin in the milk ducts of the breast and usually can’t be felt. Symptoms include a bloody or clear nipple discharge.

Intravenous or IV
Being within or entering the body through the veins. 

Invasive Breast Cancer
Cancer that has spread from the original location (milk ducts or lobules) into the surrounding breast tissue and possibly into the lymph nodes and other parts of the body. Invasive ductal cancer begins in the milk ducts. Invasive lobular cancer begins in the lobules of the breast.

Investigational New Drug (New Experimental Treatment)
A chemical or biological drug approved for use by researchers in studies, but is not yet available outside of a clinical trial.

K

Ki-67 Rate
A common way to measure proliferation rate. The more cells the Ki-67 antibody attaches to on a tissue sample, the more likely the tumor cells are to grow and divide rapidly.

L

Lactation
The process of producing milk and breastfeeding a child.

Large Veins (Deep Veins)
The large veins deep inside the legs that carry blood from the legs back to the heart.

Leptomeningeal Metastasis
Cancer that spreads from the original tumor to the meninges (the thin layers of tissue that cover and protect the brain and spinal cord).

Lesion
Area of abnormal tissue.

Lifetime Risk
The chance of developing a disease (like breast cancer) over the course of a lifetime. For example, the lifetime risk of breast cancer for women is 1 in 8 (or about 12 percent). This means for every 8 women, one will be diagnosed with breast cancer during her lifetime.

Linear Accelerator
The device used during radiation therapy to direct X-rays into the body.

Liquid Biopsy
A test that measures levels of circulating tumor cells or circulating tumor DNA in the blood. Although the term includes the word “biopsy,” these tests are not used for breast cancer diagnosis.

Liver Scan
An image of the liver that can show the presence or absence of a tumor. 

Lobular Carcinoma in Situ (LCIS, Lobular Neoplasia in Situ)
A condition where abnormal cells grow in the lobules of the breast. LCIS increases the risk of breast cancer.

Lobular Neoplasia in Situ (see Lobular Carcinoma in Situ)  

Lobules
Ball-shaped sacs in the breast that produce milk.

Local Anesthetic
Anesthesia that only numbs the tissue in a certain area. See Anesthesia.

Local Treatment
Treatment that focuses on getting rid of the cancer from a certain (local) area. In breast cancer, the local area includes the breast, the chest wall and lymph nodes in the underarm area. Local treatment for breast cancer includes surgery and for some people, radiation therapy.

Localized Breast Cancer
Cancer that is contained in the breast and has not spread to nearby tissue, lymph nodes or other organs.

Locally Advanced Breast Cancer
Cancer that has spread beyond the breast to the chest wall, the skin of the breast or to many lymph nodes in the underarm area, but not to distant organs such as the lungs or liver.

Local Recurrence (Recurrence)
The return of cancer to the same (treated) breast or to the same side chest wall.

Lump
Any mass in the breast or elsewhere in the body.

Lumpectomy (Breast Conserving Surgery)
Breast surgery that removes only the tumor and a small rim of normal tissue around it, leaving most of the breast skin and tissue in place. 

Lymph Nodes (Lymph Glands)
Small groups of immune cells that act as filters for the lymphatic system. Clusters of lymph nodes are found in the underarms, groin, neck, chest and abdomen.  

Lymph Node Status
Shows whether or not cancer has spread to the lymph nodes. Lymph node-positive means the lymph nodes contain cancer (the cancer has spread to the lymph nodes). Lymph node-negative means the lymph nodes do not contain cancer. See Lymph Nodes.

Lymphatic System
The network of lymph nodes and vessels in the body.

Lymphedema
Swelling due to poor draining of lymph fluid that can occur after surgery to remove lymph nodes or after radiation therapy to the area. Most often occurs in the upper limbs (arm, hands or fingers), but can occur in other parts of the body.

Lymphoscintigraphy
An imaging method used to check the lymph system for diseases or conditions, such as lymphedema.

M

Macrobiotics (Macrobiotic Diet)
A complementary or integrative dietary therapy that includes a mostly vegetarian, organic food diet with certain methods of food preparation.

Magnetic Resonance Imaging (see MRI)

Malignant
Cancerous.

Mammary Duct (see Duct)

Mammary Duct Ectasia
A benign (not cancer) breast condition resulting from inflammation (swelling) and enlargement of the ducts behind the nipple. Often there are no symptoms, but calcifications seen on a mammogram may point to its presence. No treatment is needed unless there are symptoms such as burning, pain or itching in the nipple area.

Mammary Glands
The breast glands that produce milk.

Mammogram
An X-ray image of the breast.

Margins
The rim of normal tissue surrounding a tumor that’s removed during breast surgery. A margin is clean (also known as uninvolved, negative or clear) if there’s only normal tissue (and no cancer cells) at the edges. Clean margins show the entire tumor was removed. With involved (also known as positive) margins, normal tissue doesn’t completely surround the tumor. This means the entire tumor was not removed and more surgery may be needed to get clean margins.

Mastectomy
Surgical removal of the breast. The exact procedure depends on the diagnosis. See Total Mastectomy and Modified Radical Mastectomy.

Mastalgia
Breast pain related to menstrual periods or other causes.

Mastitis
An inflammation (swelling) of the breast usually occurring during breastfeeding. Symptoms include pain, nipple discharge, fever, redness and hardness over an area of the breast.

Maximum Tolerated Dose
The highest amount of a drug or treatment that doesn’t cause too many side effects. This dose is determined in clinical trials that find the highest dose with acceptable side effects to participants.

Mean
The average of a group of numbers.

Mean Survival Time
The average time from the start of treatment (or diagnosis) that people in a study stay alive.

Median
The middle value (50^th percentile) of a group of numbers.

Medical Oncologist
A physician who specializes in the treatment of cancer using chemotherapy, hormone therapy, HER2-targeted therapy and other drug therapies.

Melatonin
Hormone made by the pineal gland in the brain. It’s an important part of the body’s internal timing system.

Menarche
The first menstrual period.  

Menopausal Hormone Therapy (Postmenopausal Hormone Use, Hormone Replacement Therapy)
The use of hormone pills containing estrogen (with or without progestin) to ease symptoms of menopause.

Menopause
The ending of the normal menstrual cycle in women. It occurs most often in the late 40s or early 50s.

Meta-Analysis
A method for taking the results reported in a group of studies and averaging them to come up with a single, summary result.

Metabolized
The chemical process in the body that breaks down drugs and food. 

Metastasis
The spread of cancer to other organs through the lymphatic and/or circulatory system. Metastases is the plural of metastasis.

Metastasize
When cancer cells spread to other organs through the lymphatic and/or circulatory system.

Metastatic Breast Cancer
Breast cancer that has spread beyond the breast to other organs in the body (most often the bones, lungs, liver or brain). Metastatic breast cancer is not a specific type of breast cancer, but rather the most advanced stage (stage IV) of breast cancer.

Microcalcifications
Small, clustered deposits of calcium in the breast that may be seen on a mammogram. These may or may not be related to breast cancer.

Microvascular Surgery
Surgery that involves connecting small blood vessels.

Modified Radical Mastectomy
Surgical removal of the breast, the lining of the chest muscles and some of the lymph nodes in the underarm area. Used to treat early and locally advanced breast cancer.

Molecular Breast Imaging (Nuclear Medicine Imaging of the Breast)
An imaging technique that uses short-term radioactive agents given through an IV. Cancer cells absorb these agents and can be imaged with a special camera. Molecular breast imaging is not a standard breast cancer screening tool. Breast-specific gamma imaging and positron emission mammography are types of molecular breast imaging.

Monoclonal Antibodies
Immune proteins that can locate and bind to cancer cells. They can be used alone or they can be used to deliver drugs, toxins or radioactive material directly to tumor cells. Trastuzumab (Herceptin) is an example of a monoclonal antibody used to treat breast cancer.

Morphea (Radiation-Induced Morphea, Post-Irradiation Morphea)
A rare scleroderma-like condition caused by radiation therapy to the breast. The skin and connective tissue of the breast hardens and tightens, causing pain and affecting the look and shape of the breast. (This is a more severe condition than the usual skin changes people getting radiation therapy may have.)

Mortality Rate
Number of deaths in a given group of people over a certain period of time.  

MRI (Magnetic Resonance Imaging)
An imaging technique that uses a magnet linked to a computer to make detailed pictures of organs or soft tissues in the body.

mTOR (Mammalian Target of Rapamycin) Inhibitors
A class of drugs that may increase the benefit of hormone therapy. Everolimus (Afinitor) is an example of an mTOR inhibitor.

Multifocal Tumors (Multicentric Tumors)
One or more tumors that develop from the original breast tumor.

Multimodality Therapy
Use of 2 or more treatment methods (such as surgery, radiation therapy, chemotherapy, hormone therapy and HER2-targeted therapy) in combination, or one after the other, to get the best results.

Mutation (Gene Mutation) 
Any change in the DNA (the information contained in a gene) of a cell. Gene mutations can be harmful, beneficial or have no effect.

N

Naturopathy (Naturopathic Medicine)
A medical system based on a belief in using natural elements to maintain health and to help the body heal itself. It includes nutrition and massage.

Needle Localization (see Wire Localization)  

Neoadjuvant Chemotherapy (Induction Chemotherapy, Primary Chemotherapy, Preoperative Chemotherapy)
Chemotherapy used as a first treatment (before surgery). Often used for large or locally-advanced breast cancers (including inflammatory breast cancer) to shrink tumors before surgery.

Neoadjuvant Hormone Therapy
Hormone therapy used as a first treatment (before surgery). Often used for large or locally-advanced breast cancers to shrink tumors before surgery.

Neoadjuvant Therapy (Preoperative Therapy)
Chemotherapy or hormone therapy used as a first treatment (before surgery). Often used for large or locally-advanced breast cancers to shrink tumors before surgery.

Neoplasia
Abnormal growth.

Neoplasm
Excess number of cells in a mass that can be either benign (not cancer) or malignant (cancerous).

Nested Case-Control Study
A case-control study done within a prospective cohort study. The major advantage of a nested case-control study over a regular case-control study is the exposure of interest (for example, diet or alcohol use) is measured before any of the participants have disease. This makes it less subject to bias.

Nipple-Sparing Mastectomy
A skin-sparing mastectomy (the surgeon removes the tumor and margins as well as the fat and other tissue in the breast, but leaves as much of the skin of the breast as possible) that leaves the nipple and areola intact. This skin, the nipple and areola can then be used in breast reconstruction to cover a tissue flap or an implant instead of using skin from other parts of the body.

Node-Negative (Lymph Node-Negative)
Cancer that has not spread to the lymph nodes. See Lymph Node Status.

Node-Positive (Lymph Node-Positive)
Cancer that has spread to the lymph nodes. See Lymph Node Status.

Non-Invasive
1. In treatment, describes a procedure that doesn’t penetrate the skin (or any body opening) with a needle or other instrument.

2. In breast cancer pathology, describes a cancer that has not spread beyond the milk ducts or lobules where it began (see Carcinoma in Situ).

Nonpalpable
Describes a breast lump or abnormal area that cannot be felt but can be seen on an imaging test (such as a mammogram).

Normal Tissue
Cells that do not contain cancer.

Nuclear Medicine Imaging (see Molecular Breast Imaging)

Nucleus
The part a cell that contains the genetic material DNA. Nuclei is the plural of nucleus.

O

Observational Study
A research study where participants live their daily lives as usual and report their activities to researchers.

Odds Ratio
A measure reported in case-control studies that describes the increase (or decrease) in disease risk related to a risk factor. An odds ratio is interpreted in the same way as a relative risk, though it is calculated differently.

Oligometastasis
Cancer cells that have spread (metastasis) from the original tumor and formed a small number of new metastatic tumors in a few other parts of the body. These tumors may grow more slowly than other metastatic tumors.

Oncologist
The physician in charge of planning and overseeing cancer treatment.

Oophorectomy
Surgical removal of the ovaries.

Opiate
A drug that contains opium or a substance made from opium and is used to treat pain.

Opioid
A drug that does not contain opium or any substances made from opium, but has similar effects to opium, including addiction, and is used to treat pain.

Osteoporosis
A condition marked by a loss of bone mass and density, causing bones to become fragile.

Out-of-Network Provider
Any health care provider or medical center (hospital or other treatment center) that is not part of a person’s group health plan or health maintenance organization (HMO).

Ovarian Suppression
The use of drug therapy or surgery to prevent the ovaries from making estrogen. It stops menstrual periods and lowers hormone levels in the body (similar to a natural menopause). This slows the growth of estrogen receptor-positive breast cancer in premenopausal women by preventing the tumor from getting the estrogen it needs to grow. Ovarian suppression is always given in combination with tamoxifen or an aromatase inhibitor.

Over-Diagnosis
Diagnosis that occurs when a mammogram finds ductal carcinoma in situ (DCIS) or a small, invasive breast cancer that would have never caused symptoms or problems if left untreated. These breast cancers may never grow or a person may die from another cause before the breast cancer becomes a problem.

Over-Treatment
Treatment for ductal carcinoma in situ (DCIS) or a small, invasive breast cancer that would have never caused symptoms or problems if left untreated.  

Overall Survival (Overall Survival Rate, Survival)
The percentage of people alive for a certain period of time after diagnosis with a disease (such as breast cancer) or treatment for a disease.

P

Paget Disease of the Breast (Paget Disease of the Nipple)
A rare cancer in the skin of the nipple or in the skin closely surrounding the nipple that is usually, but not always, found with an underlying breast cancer (ductal in situ carcinoma or invasive breast cancer). In these cases, the tumor grows from underneath the nipple and breaks out onto the surface of the nipple.

Palliative Care (Palliative Therapy, Palliation)
Care at any stage of disease focused on relieving or preventing symptoms (like pain) rather than treating disease. It’s part of care for people with early breast cancer as well as for those with metastatic breast cancer.

Palpable
Describes a breast lump or abnormal area that can be felt during a clinical breast exam.

Palpation
To examine, using the hands and fingers.

PARP (Poly(ADP-ribose) Polymerase) Inhibitors
A class of drugs that blocks an enzyme involved in tumor DNA repair (called PARP enzyme). These drugs can help chemotherapy better kill cancer cells. Olaparib (Lynparza) is an example of a PARP inhibitor used to treat breast cancer.

Partial Mastectomy (see Lumpectomy)

Pathologic Response
A measure describing how much of the tumor is left in the breast and lymph nodes after neoadjuvant (before surgery) therapy. The pathologic response gives some information about prognosis. A complete pathologic response means there is no invasive cancer in the tissue removed during breast surgery.

Pathologist
The physician who uses a microscope to study the breast tissue and lymph nodes removed during biopsy or surgery and determines whether or not the cells contain cancer.

Patient Navigator
A person who works to help patients effectively navigate a fragmented health care system by removing an individual’s barriers to quality care.

Peri-Menopause
The time in a woman’s life prior to menopause when menstrual periods become irregular and some menopausal symptoms may begin.

Peripherally Inserted Central Catheter (PICC)
A small tube used to deliver medicine to the body through a vein. Instead of being reinserted for each use, a PICC is left in place to allow access for a long period of time (weeks to months).

Permanent Section
A preserved tissue sample for diagnosis. Thin slices of tissue are processed and put on a slide so that a pathologist can study them under a microscope. These sections are of better quality than frozen sections.

Perometer
A device that uses infrared light beams to measure limb volume. 

Personalized Medicine (see Precision Medicine)  

PET (Positron Emission Tomography)
A procedure where a short-term radioactive sugar is given through an IV so a scanner can show which parts of the body are consuming more sugar. Cancer cells tend to consume more sugar than normal cells do. PET is sometimes used as part of breast cancer diagnosis.

Pharmacogenomics (Pharmacogenetics)
The study of the way genes affect a person’s response to drugs to help predict which drugs may offer him/her the most benefit.

Phenotype
A characteristic in a person that results from the interaction between his/her genes and his/her environment.

Phyllodes Tumor
A rare sarcoma (cancer of the soft tissue) in the breast.

PI3 Kinase Inhibitors
A class of drugs designed to interrupt PI3 kinase signals and stop the growth of cancer cells with PIK3CA gene mutations. Alpelisib (Piqray) is an example of a PI3 kinase inhibitor used to treat breast cancer.

Pituitary Gland
A part of the brain that controls growth and other glands in the body, such as the ovaries.

Placebo
An inactive medicine sometime used to have a comparison to a new drug in a clinical study. May be called a “sugar pill.”

Pooled Analysis
A method for collecting the individual data from a group of studies, combining them into one large set of data and then analyzing the data as if they came from one big study.

Positron Emission Tomography (see PET)

Postmenopausal Hormone Use (see Menopausal Hormone Therapy) 

Precision Medicine (Personalized Medicine)
Using information about a person’s genes, the tumor’s genes, molecular characteristics of the tumor and the environment to prevent, diagnose and treat cancer (such as the use of HER2-targeted therapies ). This may also be known as personalized medicine.

Predictive Factors
Factors (such as hormone receptor status) that help guide treatment for a person’s cancer.

Predispose
To make more at risk for a disease.

Premenopausal Women
Women who have regular menstrual periods.

Premium (Insurance Premium)
The cost of insurance coverage for a certain period of time.

Preoperative Chemotherapy (see Neoadjuvant Chemotherapy)

Prevalence Rate
The proportion (percentage) of people in a population who have a certain disease, behavior or characteristic at a defined point in time.

Prevention (Risk Reduction)
Steps taken to prevent or lower the risk of a disease.

Primary Chemotherapy (see Neoadjuvant Chemotherapy)

Primary Tumor
The original cancer.

Progesterone
A hormone made by the body that is important in menstrual cycles and pregnancy. May be made in a lab (called progestin) and used in birth control pills, menopausal hormone therapy and other types of hormone treatment.

Progesterone Receptor
Specific proteins in cells that progesterone hormones attach to. A high number of progesterone receptors in a breast cancer cell often means the cancer cell needs progesterone to grow.

Progestin
Any substance (natural or made in a lab) that has some or all of the effects of progesterone in the body.

Prognosis
The expected or probable outcome or course of a disease (the chance of recovery or survival).

Prognostic Factors
Factors (such as tumor type, size and grade) that help determine prognosis.

Progression
The growth or spread of cancer, with or without treatment.

Progression-Free Survival
The length of time a person lives with metastatic cancer (such as metastatic breast cancer) before the cancer grows or spreads.

Proliferative
Rapidly growing and increasing in number. 

Prophylactic Mastectomy
Preventive surgery where one or both breasts are removed in order to prevent breast cancer. When both breasts are removed, the procedure is called bilateral prophylactic mastectomy.

Prospective Study
An observational study that follows people forward in time. See Cohort Study.

Prosthetic (Breast Prosthetic, Prosthesis)
An artificial breast form that can be worn under clothing after a mastectomy.

Protocol
An outline or plan for the use of an experimental drug, treatment or procedure in cancer therapy or diagnosis.

Punch Biopsy
Removal of a small circle of skin (with a special instrument called a punch or trephine) to be tested for cancer cells.

Q

Quadrantectomy
Surgery where one quadrant or 25 percent of the breast is removed. See Lumpectomy.

Quality of Care
Measures of how well breast cancer is treated and how well a person is cared for during and after treatment.

Quality of Life
A measure of a person’s well-being and overall enjoyment of life.

Quartiles
Categories of an exposure (such as body weight or exercise) based on 4 equal parts of the total number of people in the study.

Quantiles
Categories of an exposure (such as body weight or exercise) based on equal parts of the total number of people in the study. When the total number of people is divided into thirds, the categories are called tertiles. When the total number of people is divided into quarters, the categories are called quartiles.

R

RAD (Dose of Radiation)
Short for “radiation absorbed dose.” This term describes the amount of radiation absorbed by the tissues. One RAD is equal to 1 centigray. See Centigray.

Radial Scars (Complex Sclerosing Lesions)
A benign (not cancer) breast condition with a core of connective tissue fibers. Milk ducts and lobules grow out from this core.

Radiation Oncologist
A physician specializing in the treatment of cancer using targeted, high-energy X-rays. 

Radiation Therapy (Radiotherapy)
Treatment given by a radiation oncologist that uses targeted, high-energy X-rays to kill cancer cells.

Radical Mastectomy (Halsted Radical)
Surgical removal of the breast, chest muscles and underarm lymph nodes. Used only when the breast tumor has spread to the chest muscles.

Radio-Opaque
Does not allow radiation to pass through. A radio-opaque object will show up on an X-ray.

Radiologist
A physician who reads and interprets X-rays, mammograms and other scans related to diagnosis or follow-up. Radiologists also perform needle biopsy and wire localization procedures.

Radiotherapy (see Radiation Therapy)

Raloxifene
A drug first used to treat osteoporosis and now also used to lower the risk of breast cancer in postmenopausal women at high risk.

Randomized Controlled Trials
Studies where researchers change some participants’ behavior or provide a certain therapy to some participants to see how it affects health. Participants are randomly assigned (as if by coin toss) to either an intervention group (such as one getting a new drug) or a control group (such as one getting standard treatment).

Reconstruction (see Breast Reconstruction)  

Recurrence (Relapse)
Return of cancer. Local recurrence is the return of cancer to the same breast or the same side chest wall. Distant recurrence is the return of cancer that has spread to other parts of the body, such as the lungs, liver, bones or brain. See Metastases.

Regimen
A treatment plan.

Regional Lymph Nodes
In breast cancer, the axillary (in the underarm area) lymph nodes, infraclavicular (under the collarbone) lymph nodes, supraclavicular (above the collarbone) lymph nodes and internal mammary nodes. See Lymph Nodes.

Regression
The shrinking of a tumor. 

Relative Risk
A measure used to describe the increase (or decrease) in risk related to a specific risk factor. A relative risk is the ratio of 2 absolute risks: the numerator is the absolute risk among those with the risk factor and the denominator is the absolute risk among those without the risk factor. A relative risk that is greater than one shows a factor increases risk. A relative risk that is less than one shows a factor decreases risk. And, a relative risk of one shows the factor neither increases nor decreases risk (this means the factor is not likely related to risk of the disease). 

Relative Survival (Relative Survival Rate)
A measure used to compare the survival of people who have a certain disease with those who do not at a given time after diagnosis or treatment. The relative survival rate shows whether the disease shortens life. If relative survival is 100 percent at 5 years after treatment, there’s no difference in survival between those who have the disease and those who do not 5 years after treatment.

Retrospective Study
A study where both the exposure (such as alcohol use) and the outcome (such as breast cancer) occur before the start of the study.

Risk (of Disease)
Probability (chance) of a disease developing in a person during a specified time period.

Risk-Benefit Ratio
The relationship between the possible (or expected) side effects and benefits of a treatment or procedure.

Risk Factor
Any factor—from a lifestyle choice (such as diet) to genetics to an environmental exposure (such as radiation)—that increases or decreases a person’s risk of developing a certain disease.

RNA (Ribonucleic Acid)
A molecule made by cells containing genetic information that has been copied from DNA. RNA performs functions related to making proteins.

S

Saline
A saltwater solution similar to that found in IV fluids. Saline can be used to fill a breast implant.

Salpingo-Oophorectomy
Surgical removal of the fallopian tubes and ovaries.

Scalp Cooling
The use of a cap filled with a chilled substance during chemotherapy to reduce hair loss due to chemotherapy.

Schedules
The different combinations and timing for chemotherapy and other drugs.

Sclerosing Adenosis
Small, benign (not cancer) breast lumps caused by enlarged lobules. The lumps may be felt and may be painful.

Scintimammography (see Molecular Breast Imaging)

Screening
A test or procedure used to find cancer or a benign (not cancer) condition in a person who does not have any known problems or symptoms.

Screening Mammogram
A test used to find early signs of breast cancer in a woman who does not have any known breast problems or symptoms.

Second Primary Tumor
A second breast cancer that develops in a different location from the first. This is different from a recurrence, which is the return of the first breast cancer.

Selection Criteria
In a summary research table, the specific standards (such as study design and number of participants) a study has to meet to be included.

Selective Estrogen Receptor Degrader (SERD)
An anti-estrogen drug that binds to the estrogen receptor in a tumor cell, causing the receptor to be broken down by the cell. Fulvestrant and elacestrant are SERDs.

Selective Estrogen Receptor Modulator (SERM)
A drug that can either block the effects of estrogen or behave like estrogen, depending on the part of the body being treated. Tamoxifen and raloxifene are SERMs.

Sensitivity
A quality of a screening test that shows the proportion (or percentage) of people who truly have the condition of interest who test positive for that condition. A test that had 100 percent sensitivity would correctly identify everyone who has the condition (but would have a lot of false positives).

Sentinel Node Biopsy
The surgical removal and testing of the sentinel node(s) (first axillary node(s) in the underarm area filtering lymph fluid from the tumor site) to see if the node(s) contains cancer cells.

Silicone Gel
Medical-grade, solid form of silicone used for breast implants. Silicone implants can mimic the feel of a natural breast better than saline implants.  

Simple Cyst
A round or oval-shaped fluid-filled sac. Findings from a breast ultrasound show the cyst only contains fluid.

Simple Mastectomy (see Total Mastectomy)

Skin-Sparing Mastectomy
A procedure that surgically removes the breast, but keeps intact as much of the skin that surrounds the breast as possible. This skin can then be used in breast reconstruction to cover a tissue flap or an implant instead of having to use skin from other parts of the body.

Sonogram (see Ultrasound)

Specificity 
A quality of a screening test that shows the proportion (or percentage) of people who truly do not have the condition of interest who test negative for the condition. A test that had 100 percent specificity would correctly identify everyone who did not have the condition (but would have a lot of false negatives).

Stage of Cancer (Cancer Stage)
A way to indicate the extent of the cancer within the body. The most widely used staging method for breast cancer is the TNM system, which uses Tumor size, lymph Node status and the absence or presence of Metastases in addition to other factors to classify breast cancers.  

Staging (Cancer Staging)
Doing tests to learn the extent of the cancer within the body (the cancer stage 0 to IV). Knowing the cancer stage helps determine what treatment is needed and how effective this treatment may be in getting rid of the cancer and prolonging life.

Standard Treatment (Standard of Care)
The usual treatment of a disease or condition currently in widespread use and considered to be of proven effectiveness on the basis of scientific evidence and past experience.

Statistical Significance
Describes whether or not the result of a study is likely due to chance. For example, a statistically significant result likely shows a true link between a risk factor and breast cancer, or a treatment and improved survival.

Stereotactic Needle Biopsy
Core needle biopsy done with the use of stereotactic (3-dimensional) mammography guidance.

Stereotactic Mammography
Three-dimensional mammography used to guide a needle biopsy.

Supraclavicular Lymph Nodes
The lymph nodes above the clavicle (collarbone). See Lymph Nodes.

Surgeon
Physician who performs any surgery, including surgical biopsies and other procedures.

Surgical Oncologist
A physician specializing in the treatment of cancer using surgical procedures.

Survival (see Overall Survival and Relative Survival)

Survivors (Breast Cancer Survivors)
People with a history of breast cancer, from the time of diagnosis to the end of their lives.

Survivorship
The emotional and physical health, life and care of a person diagnosed with breast cancer from the time of diagnosis until the end of life.

Systemic (Adjuvant) Treatment
Treatment given in addition to surgery and radiation therapy to treat breast cancer that may have spread to other parts of the body. It may include chemotherapy, hormone therapy and/or HER2-targeted therapy.

T

Tamoxifen (Nolvadex)
A hormone therapy drug (taken in pill form) used to treat early and advanced stage breast cancers that are hormone receptor-positive. These breast cancers need estrogen to grow. Tamoxifen stops or slows the growth of these tumors by blocking estrogen from attaching to hormone receptor in the cancer cells. 

Targeted Therapy
Drug therapies designed to attack specific molecules or proteins involved in the development of cancer. HER2-targeted therapies, such as trastuzumab (Herceptin), and PI3 kinase inhibitors, such as alpelisib (Piqray), are examples of targeted therapies used to treat breast cancer.

Tertiles
Categories of an exposure (such as body weight or exercise) based on 3 equal parts of the total number of people in the study.

Therapeutic Touch
A complementary or integrative therapy where trained practitioners enter a semi-meditative state and hold their hands just above a person’s body to sense energy imbalances due to illness. Healing energy is then said to transfer to the person.

Thermography
An imaging technique that uses infrared light to measure temperature differences on the surface of the breast. The U.S. Food and Drug Administration (FDA) and the American College of Radiology do not support the use of thermography as a breast cancer screening tool.

Tissue
A group or layer of cells.

Tomosynthesis (see Breast Tomosynthesis) 

Total Mastectomy (Simple Mastectomy)
Surgical removal of the breast but no other tissue or nodes. Used for the treatment of ductal carcinoma in situ and, in some cases, breast cancer recurrence. Also used in prophylactic mastectomy. 

Trastuzumab (Herceptin)
A drug that is a specially made antibody that targets cancers with a lot of HER2 protein on the cancer cells. When attached to the HER2 protein, trastuzumab slows or stops the growth of the cancer cells. Trastuzumab is used to treat HER2-positive breast cancer. Herceptin is the brand name for trastuzumab.

Triple Negative Breast Cancer
A breast cancer that is estrogen receptor-negative, progesterone receptor-negative and HER2-negative.

Triple Positive Breast Cancer
A breast cancer that is estrogen receptor-positive, progesterone receptor-positive and HER2-positive.

Tumor
An abnormal growth or mass of tissue that may be benign (not cancer) or malignant (cancerous). 

Tumor Grade
Describes how closely cancer cells look like normal cells. Grade 1 tumors have cells that are slow-growing and look the most like normal cells. Grade 3 tumors have cells that are fast-growing and look very abnormal. Grade 2 tumors fall in between grade 1 and grade 3.

Tumor Heterogeneity
Differences between cancer cells within the same tumor.

Tumor Infiltrating Lymphocytes (TILs)
Immune cells that have moved from the blood to a tumor. Higher levels of TILs in early-stage triple negative breast cancers may be related to improved treatment response and better survival.

Tumor Marker
A substance found in blood that may be a sign of metastatic breast cancer. Tumor markers are found in both normal cells and cancer cells, but they are made in larger amounts by cancer cells. A tumor marker may help indicate metastatic breast cancer treatment activity. The term tumor marker may also be used more broadly to refer to characteristics of tumor cells such as hormone receptors.  

Tumor Profiling (Gene Expression Profiling, Molecular Profiling, Genomic Testing)
Tests that give information about thousands of genes in cancer cells. Specific genes (or combinations of genes) may give information useful in prognosis and in making treatment decisions.

Two-Step Procedure
Biopsy and further surgical treatment done at 2 separate times.

Tyrosine-Kinase Inhibitors
A class of drugs that target enzymes important for cell functions (called tyrosine-kinase enzymes). These drugs can block tyrosine-kinase enzymes at many points along the cancer growth pathway. Lapatinib (Tykerb) is an example of a tyrosine-kinase inhibitor used to treat breast cancer.

U 

Ultrasound (Sonogram)
Diagnostic test that uses sound waves to make images of tissues and organs. Tissues of different densities reflect sound waves differently.

Usual Hyperplasia
A benign (not cancer) breast condition where breast cells are growing rapidly (proliferating). The proliferating cells look normal under a microscope. Although usual hyperplasia is not breast cancer, it increases the risk of breast cancer.

V 

Vaginal Atrophy (Atrophic Vaginitis)
A condition where the lining of the vagina becomes thin and dry due to a decrease in estrogen. It causes vaginal dryness, pain during intercourse and other symptoms. It most commonly occurs in women who have gone through menopause.

Variant (Gene Variant)
Any change in the DNA (the information contained in a gene) of a cell. A gene variant can be harmful, beneficial or have no effect.

W 

Wire Localization (Needle Localization)
Insertion of a very thin wire into the breast to highlight the location of an abnormal area so it can be removed during a biopsy or a lumpectomy.

X

X-Ray
Radiation that, at low levels, can be used to make images of the inside of the body. For example, a mammogram is an X-ray image of the breast. At high levels of radiation, X-rays can be used in cancer treatment.

Parts of this glossary were adapted from the National Cancer Institute’s Dictionary of Cancer Terms, the American Cancer Society’s Cancer Glossary and the National Comprehensive Cancer Network’s Patient and Caregiver Resources: Dictionary.

Updated 09/16/24