Understanding Your Pathology Report

Two fundamental steps are taken in the management of patients with breast cancer. The first step is to make the diagnosis. The diagnosis is established by taking a small amount of tissue from the tumor and examining it under the microscope. The second step is the definitive surgical treatment which involves the removal of the tumor and one or more axillary (under-arm) lymph nodes. Each time tissue is removed, a pathology report is provided. These reports provide the foundation upon which clinical decisions are made. It is important for a woman to keep copies of all pathology reports, and to understand the basic message in each report.

Invasive vs. Non-Invasive

The first question to be answered is….. ‘What is my diagnosis?’ In other words, is my lump or the spot on my mammogram benign (i.e. not cancer), or malignant (i.e. cancer). Assuming that the diagnosis is malignant, the next question to answer is….”is the cancer invasive or non-invasive?”

Non-invasive cancers are basically curable. Invasive cancers have the potential to spread beyond the breast and require more complex therapy. This information will be clearly defined in your initial pathology report(s). The following are brief definitions of invasive and non-invasive cancers:

Non-invasive Breast Cancer

DCIS (Ductal carcinoma in situ): In DCIS the cancer cells are confined to the ducts and have not invaded the surrounding tissue. For this reason these tumors are considered curable with wide removal of the tumor and surrounding tissue. In many cases radiation will also be required. In situation in which mastectomy is performed, no radiation is required, and immediate reconstruction is usually recommended.

LCIS (Lobular carcinoma in situ): This tumor starts in milk producing structures of the breast called lobules. This tumor does not invade. In fact it is not a true cancer, and should be thought of only as a risk factor for the future development of breast cancer. The majority of patients with LCIS do not need surgery, and are managed with careful observation. In some cases tamoxifen is recommended for risk reduction. In rare circumstances bilateral mastectomy with immediate reconstruction is performed.

Invasive Breast Cancer

Invasive ductal or infiltrating ductal carcinoma: This is a cancer that starts in the milk ducts and invades the surrounding tissue. It is the most common form of breast cancer.

Invasive lobular carcinoma or infiltrating lobular carcinoma: This tumor arises from the milk producing lobules and invades the surrounding tissue. Lobular cancers are often difficult to visualize on the mammogram, and are usually more difficult to detect on physical examination. The treatment for invasive lobular cancer is essentially the same as that for infiltrating ductal carcinoma.


Once the diagnosis has been made, the next major question is…..”What is my prognosis?” The key to understanding your prognosis is your final pathology report, which is provided after the completion of your definitive surgical procedure. The final report includes a long list of tumor characteristics that include the size and type of the tumor, the status of the lymph nodes, and other markers as described below:

  1. Type of tumor: Invasive or non-invasive (see initial discussion)
  2. Size of tumor: The report will note the size of the invasive tumor in centimeters (1 inch equals 2.54 centimeters or 25.4 millimeters). The size of an invasive cancer is a key element in determining prognosis.
  3. Lymph nodes: The report will state the number of lymph nodes removed and the number of lymph nodes, if any, that contain cancer cells. This is a very important factor and together with size, determines the stage of the cancer (see below for staging).
  4. Margins: The margin refers to the distance between the tumor and the edge of the surgical specimen.
  5. Hormone receptors: Hormone receptors are like on/off switches on the surface of the cancer cell that respond to hormones in the blood stream. The hormone receptors that influence breast cancer prognosis are estrogen and progesterone receptors. If a tumor is positive for estrogen or progesterone it is more likely to respond to estrogen blocking drugs such as tamoxifen. In general, hormone negative tumors tend to be more aggressive, and are more likely to be treated with chemotherapy.
  6. Differentiation or grade: In this analysis tumor cells are compared to normal breast cells. In Grade 1 (low grade or well differentiated) the cells are only slightly different from normal cells. These tumors tend to grow slowly. In Grade 3, the cells are markedly different from normal cells, and they tend to be faster growing tumors. Grade 2 tumors tend to be somewhere in between.
  7. Lymphatic invasion: The breast has a network of lymph channels that can drain tissue around the breast tumor. They connect with the lymph nodes under the arm. If cancer cells are found in these lymph channels, it suggests that the tumor may be more aggressive.
  8. Cancer genes: A new test that is now commonly performed on the tumor to evaluate the status of the HER2/neu receptors. HER2/neu is a gene that controls how cells grow, divide, and repair themselves. These genes direct the production of proteins called HER2 receptors. If the cell makes too many copies of these receptors it tends to grow faster. There is a new treatment called Herceptin that can effectively treat cancers that have this mutation.
  9. Bloom-Richardson score (SBR): This is the most commonly used cancer grading system. The score ranges from 3 (low grade: best prognosis) to 9 (highest grade); scores of 6 and 7 are considered intermediated grade. The score is based on the microscopic examination of the tumor cells. Three characteristics of the cells are evaluated, and each is grade on a scale of 1-3. The characteristics that are evaluated by the pathologists are: 1) cell division: the more mitosis, the higher the score, 2) cell structure: the less the formation of normal glandular structures, the higher the score, and 3) nuclear grade: the more irregular the nucleus the higher the score.

Stages of Breast Cancer

  • Stage O: This stage applies to non-invasive breast cancer.
  • Stage I: In stage I the invasive breast cancer is 2 centimeters or less in diameter, and the lymph nodes are negative.
  • Stage II A: lymph nodes positive and tumor less than 2 cm., or lymph nodes negative and tumor between 2 and 5 cm.
  • Stage II B: tumor between 2 and 5 cm and lymph nodes positive, or tumor more than 5 cm. and lymph nodes negative.
  • Stage III A: fixed or matted lymph nodes in axilla with any size tumor, or tumor more than 5 cm with positive, but non-matted lymph nodes in axilla.
  • Stage III B: tumor with extension to skin, chest wall, or inflammatory breast cancer
  • Stage III C: more than 10 positive axillary lymph nodes, infraclavicular lymph nodes, or combinations of positive axillary and internal mammary lymph nodes.
  • Stage IV: The tumor has spread to other parts of the body such as the bone, lung, liver, etc.
  • Recurrent cancer: In recurrent cancer, the disease has come back despite treatment. The cancer can grow in the breast or chest wall (local recurrence), or in distant organs, bones, or lymph nodes (distant metastases).