Reading Your Pathology Report After Neoadjuvant Therapy

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

The goal of neoadjuvant therapy is to shrink the cancer in the breast and/or lymph nodes in the underarm area (axillary lymph nodes). Neoadjuvant therapy may shrink a tumor enough so a lumpectomy becomes an option to mastectomy.

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 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.

TNM staging system and neoadjuvant therapy

The most common way breast cancer is staged 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.

yT = Tumor stage after neoadjuvant therapy

yN = 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-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. The largest continuous area will be reported as the tumor size. You’ll see the letter “m” to note there were multiple areas of cancer in the breast.

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 [33].

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.

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 “yp” 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 ultrasound or 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

ypNXAxillary and other nearby lymph nodes cannot be assessed (for example, they were not removed during surgery)
ypN0Axillary and other nearby lymph nodes do not have cancer or only have isolated tumor cells (individual cancer cells), when looked at under a microscope
ypN1Micrometastases (very small clusters of cancer) OR 1–3 axillary lymph nodes have cancer AND/OR Internal mammary nodes have cancer or micrometastases (very small clusters of cancer cells) found on sentinel node biopsy
ypN24–9 axillary lymph nodes have cancer OR

Internal mammary nodes have cancer, but axillary lymph nodes do not have cancer
ypN310 or more axillary lymph nodes have cancer OR

Infraclavicular (under the clavicle) 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 found on sentinel node biopsy OR

Supraclavicular (above the clavicle) nodes have cancer
Adapted from American Joint Committee on Cancer materials [33].

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 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 may be included on your pathology report.

The breast cancer’s response to neoadjuvant treatment gives useful information about prognosis.

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 breast cancer.

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

Learn more about pathologic complete response.

Residual breast cancer

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

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

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 breast cancer there is in the breast and lymph nodes:

  • RCB-0 = No residual breast cancer
  • RCB-I = Small amount of residual breast cancer
  • RCB-II = Moderate amount of residual breast cancer
  • RCB-III = Extensive residual breast cancer

Learn more about the contents of a pathology report.

Pathology tests repeated after surgery for breast cancer

Sometimes, tests done on the biopsy tissue (that diagnosed the breast cancer), such as hormone receptors status and tumor grade, are repeated on the tissue removed during breast cancer surgery.

It’s not clear whether repeating these tests is helpful to prognosis or treatment.

Other information on a pathology report

Other information on a pathology report are 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 12/17/20