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Breast Cancer Basics

Your Pathology Report

A pathology report is developed every time a tissue or cell sample is tested for the presence of abnormal and cancerous cells. This includes results after an initial biopsy, lumpectomy (a surgical operation to remove a tumor and some of the surrounding tissue from the breast) and mastectomy (a surgical operation to remove the whole breast).

The results of all of these tests together form your complete pathology report and can be used by you and your health care team to make decisions about your treatment and care. In addition to staging, your pathology report will determine the following:

  • The pathology report will identify if the cell or tissue samples are cancerous or non-cancerous. If the suspicious cells are found to be non-cancerous the report states that the cells are benign. Your healthcare provider may still want to monitor and follow-up with you in this case.
  • If cancerous cells are detected, also known as malignant cells, the report may indicate whether the cancer is non-invasive, meaning it has not spread outside of the lobule or duct (also called in situ) or invasive, meaning that the tumour has spread outside of the lobule or duct.
  • The report also assigns the tumour sample a grade, which provides a measure of how different the cancer cells are in comparison to normal, healthy cells.  There are three breast cancer grades. In Grade 1, the cells are just slightly different in appearance and organization from normal cells. These tumors are called low-grade, meaning the cells look almost normal under a microscope, and well-differentiated, indicating that the cells tend to more closely resemble normal cells and likely grow and spread slower than other grades. Grade 2 cancer cells do not resemble normal cells and are considered moderately graded and differentiated. These cells also tend to grow slightly faster than normal. Grade 3 cells are considered high-grade, meaning the cells look abnormal under a microscope, and are poorly differentiated, meaning they significantly differ in appearance, organization and structure from normal cells. These cells grow and spread quickly.
  • The next item in the pathology report is the surgical margins.  During surgery to remove cancer, the surgeon takes out the cancer with an additional area of normal tissue (margin) attached to it. This rim of normal tissue is examined to determine that it is clear of cancerous cells. If the margins are negative, they are clear of tumour cells.  Positive means the cancerous cells appear at the edge of the sample, and additional surgery may be necessary. Close means that cancer cells are found near the edge of the sample, but not directly at the edges and may require additional surgery. It is important to note that there is no standard definition for how wide a margin must be to declare a tumour clear of cancerous cells. Speak to your healthcare provider if you have any questions about your surgical margins.
  • The pathology report also looks at lymphovascular invasion, which is the entry of breast cancer cells into the fluid vessels (blood or lymph) in the breast. In the pathology report, lymphovascular invasion is reported as either being present or absent.  If present, this can indicate an increased risk of the cancer spreading beyond the breast or returning in the future after a period of not being detected.
  • Another item in the pathology report examines lymph node involvement. Lymph nodes work as filters for the lymphatic system in the body. Lymph fluid flows between cells and picks up debris, circulating it to the lymph node for filtration.  The presence of cancer cells in the lymph nodes is associated with an increased risk of the cancer spreading and is called a positive result. A negative result, means that the lymph nodes are clear of cancer cells. The pathology report examines the number of lymph nodes that contain cancer cells, as well as the amount of cancer cells in each lymph node. The report may also state whether the cancer has spread beyond the lymph nodes.
  • Finally, the pathology report looks at hormone status (estrogen or progesterone receptor positive or negative) and HER2 status.

Once you understand your pathology report, you are better prepared to partner with your medical team in making treatment decisions.

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