Invasive Lobular Breast Cancer
Watch our Mission Moment webinar, Invasive Lobular Breast Cancer.
Read our fact sheet on invasive lobular breast cancer.
What is invasive lobular breast cancer?
Invasive lobular cancer or infiltrating lobular carcinoma (ILC) is invasive breast cancer that begins in the lobules of the breast. The lobules are small, round sacs in the breast that produce milk for breastfeeding.
With ILC, the cancer cells in the lobules invade nearby breast tissue and may travel from the breast to other parts of the body.
Learn more about breast anatomy.
How common is invasive lobular breast cancer?
Invasive lobular cancer (ILC) is the second most common type of invasive breast cancer (invasive ductal cancer (IDC) is the most common) [112]. About 5% to 10% of invasive breast cancers are ILC [112-113].
Compared to IDC, ILC tends to have a larger tumor size at diagnosis, but a lower tumor grade [112,114].
Warning signs of invasive lobular breast cancer
The warning signs of invasive lobular cancer are the same as for other breast cancers.
If you notice a change in your breast or underarm area, see your health care provider.
Find images and information about the warning signs of breast cancer.
What does invasive lobular breast cancer look like under a microscope?
Under a microscope, invasive lobular cancer (ILC) cells most often appear in a single file order. Because ILC tumors grow in this way, there may not be a mass (lump) present. This can make ILC harder to find on a mammogram than some other breast cancers.
Learn more about types of breast tumors.
Multicentric and bilateral invasive lobular breast cancer
Compared to invasive ductal cancer, invasive lobular cancer (ILC) is more likely to be [112,115]:
- Multicentric (when there’s more than one tumor in the breast)
- Bilateral (when cancer occurs in both breasts)
One study found about 20% of women with ILC have bilateral breast cancer at the time of diagnosis [116].
Treatment for invasive lobular breast cancer
Treatment for invasive lobular cancer (ILC) is planned in the same way as treatment is planned for all breast cancers. Treatment is based on breast cancer stage and other factors, such as hormone receptor status and HER2 status.
ILC tends to be [112,114]:
These and other factors guide treatment. For example, hormone receptor-positive breast cancers can be treated with hormone therapies.
Treatment for breast cancer is not based on whether the cancer is ILC, invasive ductal cancer or other tumor type.
Learn more about factors that guide breast cancer treatment.
Learn about treatment for early breast cancer.
Learn about treatment for metastatic breast cancer.
Early invasive lobular breast cancer and chemotherapy
Most cases of invasive lobular cancer (ILC) are hormone receptor-positive and HER2-negative [112,114]. Some findings show chemotherapy (in addition to hormone therapy) may not benefit all people with hormone receptor-positive, HER2-negative ILC [117].
Oncotype DX® is a test of tumor tissue that can help determine the benefit of adding chemotherapy to treatment for some hormone receptor-positive, HER2-negative early breast cancers. It can help identify some people with hormone receptor-positive, HER2-negative ILC who may get a survival benefit from chemotherapy (in addition to hormone therapy) [118].
Learn more about Oncotype DX.
Learn more about chemotherapy.
Invasive lobular breast cancer, recurrence and survival
Hormone receptor status, breast cancer recurrence and survival
The hormone receptor status of breast cancer is related recurrence (a return of breast cancer) and survival. Hormone receptor-positive breast cancers have different patterns of recurrence and survival than hormone receptor-negative breast cancers do.
While invasive lobular cancer (ILC) is usually hormone receptor-positive, invasive ductal cancer (IDC) can be hormone receptor-positive or hormone receptor-negative [112,114]. This difference makes it hard to compare recurrence and survival for ILC and IDC directly.
Invasive lobular breast cancer recurrence and survival
In the first 5 years after diagnosis, hormone receptor-positive breast cancers (such as most ILC) tend to have a lower risk of breast cancer recurrence than hormone receptor-negative breast cancers (such as some IDC) [12]. So, in the first 5 after diagnosis, women with hormone receptor-positive cancers tend to have better breast cancer survival than women with hormone receptor-negative cancers [12,119]. Similarly, women with ILC tend to have better survival in the first 5-10 years after diagnosis than women with IDC [120-121].
Hormone receptor-positive breast cancers can recur more than 10 years after diagnosis, while such late recurrences are rare for hormone receptor-negative cancers [12,122]. This may explain some of the difference in longer-term breast cancer survival between women with ILC and women with IDC. Survival 10 years after diagnosis tends to be worse women with ILC than for women with IDC [120-121].
Most important factors related to invasive lobular breast cancer survival
As with all breast cancers, the most important factors related to survival for ILC are cancer stage and tumor grade.
Learn more about the risk of breast cancer recurrence.
Learn more about breast cancer survival rates.
Invasive lobular breast cancer and sites of metastasis
Metastatic breast cancer (also called stage IV or advanced breast cancer) is breast cancer that has spread beyond the breast and nearby lymph nodes to other parts of the body.
The most common sites of breast cancer metastasis are the bones, lungs, liver and brain. While invasive lobular cancer (ILC) can metastasize to these sites, it can also spread to sites not common with other breast cancers. For example, ILC sometimes may metastasize to the ovaries or the gastrointestinal tract (including the stomach, colon and rectum) [123].
Watch Susan G. Komen®’s MBC Impact Series, Metastatic Lobular Breast Cancer.
Learn more about metastatic breast cancer.
Risk factors
Risk factors for invasive lobular cancer (ILC) are the same as those for other breast cancers.
However, a couple of factors may be related more often to ILC than other breast cancers.
Learn more about risk factors for breast cancer.
CDH1 inherited gene mutations
CDHI inherited gene mutations increase the risk of breast cancer [124-124]. CDHI gene mutations are rare. They are found in about 1 in 5,000 people [126].
People with a CDH1 inherited gene mutation have a 40%-60% lifetime risk of breast cancer [124]. CDH1 gene mutations appear to be related more often to ILC than invasive ductal cancer (IDC) [127].
Having a CDHI inherited gene mutation also increases a person’s risk of diffuse gastric (stomach) cancer [124].
The National Comprehensive Cancer Network (NCCN) recommends genetic testing for people diagnosed with ILC who have a personal or family history of diffuse gastric cancer [124].
Learn more about inherited gene mutations.
Learn about genetic testing.
Menopausal hormone therapy
Menopausal hormone therapy (MHT) is also called postmenopausal hormone therapy and hormone replacement therapy (HRT).
The use of MHT containing estrogen plus progestin increases the risk of breast cancer [128-133]. The use of MHT containing estrogen plus progestin may be more strongly linked to the risk of ILC than to the risk of IDC [112,134].
Women who use MHT containing estrogen alone may also have an increased risk of breast cancer [129-131]. One study found the use of MHT containing estrogen alone was more strongly related to the risk of ILC than to the risk of IDC (though no increased breast cancer risk was seen among women who used MHT for less than 9 years) [112,134].
Learn more about MHT and breast cancer risk.
Learn about ways to treat menopausal symptoms.
Treatment guidelines
Although the exact treatment for breast cancer varies from person to person, evidence-based guidelines help make sure high-quality care is given. These guidelines are based on the latest research and agreement among experts.
The National Comprehensive Cancer Network (NCCN) and the American Society of Clinical Oncology (ASCO) are respected organizations that regularly review and update their guidelines.
In addition, the National Cancer Institute (NCI) has treatment overviews.
Talk with your health care team about which treatment guidelines they follow.
After you get a recommended treatment plan from your health care team, study your treatment options. Together with your health care team, make thoughtful, informed decisions that are best for you. Each treatment has risks and benefits to consider along with your own values and lifestyle.
Playing an active role
You play an active role in making treatment decisions by understanding your breast cancer diagnosis, your treatment options and possible side effects.
Together, you and your health care provider can choose treatments that fit your values and lifestyle. This is called shared decision-making.
Learn more about factors that affect treatment options.
Clinical trials for invasive lobular breast cancer
Research is ongoing to improve all areas of treatment for breast cancer.
New therapies are being studied in clinical trials. The results of these studies will decide whether these therapies will become part of the standard of care.
After discussing the benefits and risks with your health care provider, we encourage you to consider joining a clinical trial.
Susan G. Komen® Patient Care Center |
If you or a loved one needs information or resources about clinical trials, the Patient Care Center can help. Contact the Komen Breast Care Helpline at 1-877-465-6636 or email clinicaltrialinfo@komen.org. The Patient Care Center navigators offer breast cancer clinical trial education and support, such as:
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BreastCancerTrials.org in collaboration with Komen offers a custom matching service to help find clinical trials that fit your needs.
Learn more about clinical trials and find a list of resources to help you find a clinical trial.
You’re not alone
If you’ve been diagnosed with invasive lobular cancer (ILC), it’s normal to feel worried or scared about going through treatment and the side effects you may have. Many people have been where you are today. They had the same fears.
Sharing experiences and advice with others diagnosed with ILC may help. You can do this in a support group or by connecting one-on-one with another ILC survivor through a peer-mentoring program.
You can also talk with your health care providers about how you’re coping. They care about your overall well-being and can help you find ways to improve it. In addition to suggesting a support group, they may connect you to another member of your health care team, such as a social worker or patient navigator, for support. They may also refer you to a counselor.
Our Support section has a list of resources to help find local and online support groups and other resources.
Learn more about social support and support groups.
Learn about healthy ways to cope with stress.
Financial assistance
Costs related to breast cancer care can quickly become a financial burden. Dealing with finances and insurance can be overwhelming.
Learn more about insurance plans and prescription drug assistance programs.
Learn more about other financial assistance programs.
Susan G. Komen® Support Resources |
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*Please note, the information provided within Komen Perspectives articles is only current as of the date of posting. Therefore, some information may be out of date.
Updated 07/18/24
