Understanding a pathology report

Lillie Shockney, RN , BS, MA S, is the administrative director of the Johns Hopkins Avon Foundation Breast Center. She writes regular features for Living with Cancer Health monitor to help readers live well as a cancer survivor. As a breast-cancer survivor herself and healthcare professional, she speaks to audiences and has written books about breast cancer.

After you’ve heard that there’s something suspicious on your mammogram, you must spend an uneasy time awaiting your pathology report. It will be helpful if you learn the meaning of the medical terms you can expect in the report.

?Biopsies are central to identifying cancer. Most breast biopsies are done as a core biopsy, in which a hollow needle is inserted into the suspicious area to extract a small bit of tissue. A pathologist examines these cells under a microscope to determine if they are in fact cancerous.

The diagnostic biopsy

The biopsy doesn’t provide a lot of detail about the cancer. But it can distinguish the two main categories: invasive and ductal carcinoma in situ (DCIS). Invasive (or “infiltrating”) means that the cancer has traveled from the milk-producing lobules or milk ducts of the breast into the fatty breast tissue, and may have spread to nearby lymph nodes. DCIS, on the other hand, is the earliest stage of breast cancer, confined to the milk ducts. Because the initial biopsy involves only a tiny bit of tissue—and so may not be representative of cells in the entire tumor—further tests are not usually done on that tissue. This biopsy is simply to make a diagnosis.

Surgical treatment

Surgery—either lumpectomy (which removes just the tumor and a margin of healthy tissue around it) or mastec-tomy (which removes most breast tissue)—is usually the first treatment for breast cancer. It also provides a larger specimen for examination and makes possible additional laboratory tests.

The results of these tests provide “prognostic factors” that will help guide the choice of further treatment. The factors, which forecast the probable course of the cancer, are outlined below.

• Verification of the category of breast cancer present. For example, the pre-surgical biopsy may have indicated DCIS, but the final pathology shows infiltrating disease as well.
• Margins.Each surgical specimen has 6 margins, or sides (picture a cube). The surgeon’s goal is to remove the tumor along with a margin of healthy tissue around it. The status of each of the 6 margins will be documented in the pathology report.
• Grade. There are three grades. Grade 1 means the cancer is slow-growing; its cells are called “well differentiated.” Grade 2 is average-growing, and grade 3 is fast-growing (“poorly differentiated” cells). Grade 3 cancer cells, however, aren’t growing so fast that you don’t have time to make thoughtful decisions about your treatment.
• Lymph node status. When the can-cer is invasive, the surgeon will check the sentinel lymph node to determine if breast cancer cells have entered the lymphatic system. Lymph nodes are small glands where germs and immune and cancer cells collect; the sentinel node is the first node that breast cancer cells are likely to reach upon escaping the breast. If this node contains no can-cer cells, then the other nodes are probably cancer-free. The pathologist will document if a sentinel node was removed and if additional axillary (underarm) nodes were removed. Each node is examined for cancer.
• Hormone receptors. These are proteins on the surface of cells that, when activated by hormones such as estrogen or progesterone, stimulate the cells to grow. A test is done to determine the levels of these receptors. Accordingly, the tumor will be classified as ER (estrogen receptor) positive or nega-tive as well as PR (progesterone receptor) positive or negative. Having hormone receptor-positive cancer means the tumor will likely respond to therapies that block the action of these hormones.
• Her-2 receptor. This cell protein responds to a natural body growth factor. Tumor cells with high levels of this recep-tor (scored as 3+) are classified HER-2-positive. This is an unfavorable prognostic factor—although such tumors can be treated with targeted therapies that neutralize HER-2 recep-tors, such as Herceptin.

It’s important that you not over-react to any one factor in your pathology report but look at the overall picture. For additional information about a pathology report, visit www.breastcancer.org or the Johns Hopkins Breast Center Website at www.hopkinsbreastcenter.org.