Understanding Your Pathology Report After Neoadjuvant Therapy

For some people with breast cancer, treatment begins with chemotherapy, HER2-targeted therapy, immunotherapy and/or hormone therapy, rather than surgery. This is called neoadjuvant therapy or preoperative therapy.

Neoadjuvant therapy may shrink the cancer in the breast and/or lymph nodes in the underarm area (axillary lymph nodes). If it shrinks the tumor enough, a lumpectomy may become an option to a mastectomy. In some cases, response to neoadjuvant chemotherapy can help guide treatment after breast cancer surgery.

Information on a pathology report is a bit different for people who get neoadjuvant therapy compared to those who get surgery as their first treatment. This page describes pathology reports, including the information used in breast cancer staging, for people who get neoadjuvant therapy.

Neoadjuvant therapy and breast cancer staging

Breast cancers treated with neoadjuvant therapy are staged a bit differently than those treated with surgery first.

Before neoadjuvant therapy begins, the pre-treatment stage of your breast cancer may be done. If so, pre-treatment stage is determined using imaging (such as mammograms) and findings from a physical exam of the breast. This is called clinical prognostic stage.

After surgery, the stage of your breast cancer is determined using pathology information from the tissue removed during surgery. The pathologic stage after neoadjuvant therapy gives the most information on your prognosis (chances for survival).

TNM staging system and neoadjuvant therapy

The main method of pathologic staging for breast cancer is the TNM system which stands for (Tumor size, lymph Node status and Metastases).

When TNM is used after neoadjuvant therapy, you’ll see a “y” before the T and N measures on your pathology report. Otherwise, the categories are the same as those for tumors not treated with neoadjuvant therapy. A “p” means a pathologist took the measurement from the tissue removed during surgery.

ypT = Tumor stage after neoadjuvant therapy

ypN = Lymph node status after neoadjuvant therapy

Metastatic status is determined before treatment begins.

M0 = No metastases

M1 = Metastases

Neoadjuvant therapy is only used to treat non-metastatic breast cancer. So, if you get neoadjuvant therapy, you should see “M0” on your pathology report.

Tumor size after surgery

A pathologist will study the tissue removed during breast cancer surgery and take measurements. Some samples of the tissue may need to be studied under a microscope to check for small amounts of cancer.

The largest length of the tumor is the tumor size.

On your pathology report, the post-neoadjuvant treatment tumor size will be indicated with “ypT” followed by numbers and sometimes, letters. The “y” notes the measurement was taken after neoadjuvant therapy. The “p” means a pathologist took the measurement from the tissue removed during surgery.

Sometimes, there’s more than one area of cancer in the breast. You’ll see the letter “m” to note there were multiple areas of cancer in the breast. The largest continuous area will be reported as the tumor size.

Tumor size on your pathology report

The definition for each tumor size is the same whether or not you get neoadjuvant therapy. The only difference is the “y” notation before the “T” on your pathology report.

Tumor size categories after treatment with neoadjuvant therapy
ypTX: Tumor size cannot be assessed
ypT0: No tumor can be found
ypTis: Carcinoma in situ
ypT1: Tumor is 2 cm or smaller
	Subcategories of ypT1:
	ypT1mi: Very small tumor (0.1 cm or smaller)
	ypT1a: Tumor is larger than 0.1 cm, but no larger than 0.5 cm
	ypT1b: Tumor is larger than 0.5 cm, but no larger than 1 cm
	ypT1c: Tumor is larger than 1 cm, but no larger than 2 cm
ypT2: Tumor is larger than 2 cm, but no larger than 5 cm
ypT3: Tumor is larger than 5 cm
ypT4: Tumor is any size, but has spread beyond the breast tissue to the chest wall and/or skin
	Subcategories of ypT4:
	ypT4a: Tumor has spread to the chest wall
	ypT4b: Tumor has spread to the skin, but is not inflammatory breast cancer
	ypT4c: Tumor has spread to both the chest wall and skin
	ypT4d: Inflammatory breast cancer
Adapted from American Joint Commission on Cancer materials [30].

During breast surgery, the surgeon may remove one or more axillary lymph nodes. A pathologist will examine the nodes under a microscope to see whether or not they contain cancer.

Lymph node-negative means none of the axillary lymph nodes contain cancer.
Lymph node-positive means at least one axillary lymph node contains cancer.

See Figure 4.4 for a drawing of the breast and lymph nodes.

Learn more about lymph node status.

Learn about lymph node status and breast cancer staging.

Lymph node status on your pathology report

The definition for each category of lymph node status is the same whether or not you get neoadjuvant therapy.

The only difference is the “y” notation before the “N” on your pathology report. For example, pN0 and ypN0 both mean the axillary and other nearby lymph nodes don’t contain cancer.

The pre-treatment status of the lymph nodes may be included on your pathology report. This is called clinical node status and is determined using imaging (for example, with breast ultrasound or breast MRI) and findings from a physical exam. Clinical node status is noted as “cN” on a pathology report.

The table below shows pathologic lymph node status categories. See an expanded version of this table that includes all subcategories.

Pathologic lymph node status after treatment with neoadjuvant therapy
ypNX	Axillary and other nearby lymph nodes cannot be assessed (for example, they were not removed during surgery)
ypN0	Axillary and other nearby lymph nodes don’t have cancer or only have isolated tumor cells (individual cancer cells), when looked at under a microscope
ypN1	Micrometastases (very small clusters of cancer cells) OR 1–3 axillary lymph nodes have cancer AND/OR Internal mammary nodes have cancer or micrometastases found on sentinel node biopsy
ypN2	4–9 axillary lymph nodes have cancer OR Internal mammary nodes have cancer, but axillary lymph nodes don’t have cancer
ypN3	10 or more axillary lymph nodes have cancer OR Infraclavicular (under the clavicle (collar bone)) nodes have cancer OR Internal mammary nodes have cancer plus 1 or more axillary lymph nodes have cancer OR 4 or more axillary lymph nodes have cancer plus internal mammary nodes have cancer or micrometastases (very small clusters of cancer cells) found on sentinel node biopsy OR Supraclavicular (above the clavicle) nodes have cancer
Adapted from American Joint Committee on Cancer materials [30].

Clips mark the location of the breast cancer

During the biopsy that diagnosed breast cancer, a clip may have been placed in your breast to mark the location of the cancer. This clip helps guide the surgeon to the tumor bed during surgery. Sometimes, neoadjuvant therapy shrinks breast cancer so much it can be hard to find the tumor bed without this clip.

Similarly, if a lymph node with cancer was found before treatment began, a clip may have been placed to mark its location. That way, the surgeon can find and remove the lymph node during surgery, even if neoadjuvant therapy shrinks the node.

Clips are usually removed during surgery.

Neoadjuvant therapy and surgery

Neoadjuvant therapy may shrink a tumor enough so a lumpectomy becomes an option to a mastectomy.

Sometimes, imaging shows there’s no cancer left in the breast after neoadjuvant therapy. However, you will still have breast surgery.

There may be some cancer left in the tumor bed (the original site of the breast cancer) that’s too small to see on imaging. So, tissue from the tumor bed must be removed and checked to be sure.

How well did the tumor respond to neoadjuvant therapy?

After surgery, a pathologist studies the breast tissue removed. The pathologist’s findings are used to determine how well the breast cancer responded to neoadjuvant therapy. This information is included on your pathology report.

The breast cancer’s response to neoadjuvant treatment gives useful information about prognosis (chances for survival).

Pathologic complete response

Sometimes, the pathologist’s exam shows no sign of cancer in the breast or axillary lymph nodes. This is called a pathologic complete response (pCR) and means the neoadjuvant therapy got rid of all the invasive breast cancer.

A pCR can give some information about prognosis (chances for survival), but it doesn’t usually change your treatment plan.

Although a pCR is encouraging, it doesn’t mean the cancer will never return. And many people who don’t have a pCR will still do very well.

If you have a pCR, it will be noted on your pathology report.

Learn more about pathologic complete response.

Residual breast cancer

Any invasive breast cancer that remains in the breast or axillary lymph nodes after neoadjuvant therapy is called residual breast cancer. Some people have some residual breast cancer after neoadjuvant therapy.

Your pathology report will include whether or not residual invasive breast cancer was found in the breast and/or lymph nodes and the size of any residual cancer.

Residual cancer burden

Sometimes, information about residual cancer burden (RCB) is included on your pathology report.

An RCB score is determined using information on the size of the tumor and the extent of tumor cells in the breast and axillary lymph nodes after neoadjuvant therapy.

The higher the RCB score, the more residual invasive breast cancer there is in the breast and lymph nodes:

RCB-0 = No residual invasive breast cancer (same as pathologic complete response)

RCB-I = Small amount of residual invasive breast cancer

RCB-II = Moderate amount of residual invasive breast cancer

RCB-III = Extensive (a lot of) residual invasive breast cancer

Learn more about the contents of a pathology report.

Pathology tests repeated after surgery for breast cancer

You may have had tests done on the pre-treatment biopsy tissue (the tissue that diagnosed the breast cancer), such as tests for hormone receptors status and HER2 status. Sometimes, these tests are repeated on the tissue removed during breast cancer surgery to confirm the test results are the same.

It’s not clear whether repeating these tests is helpful to guide prognosis (chances for survival) or treatment.

Other information on a pathology report

Other information on a pathology report is the same for people who have neoadjuvant therapy and those who have surgery as their first breast cancer treatment.

Learn more about the contents of a pathology report.

Updated 12/20/22

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