Your Pathology Report
The pathology report is one of the most important documents you will receive during your diagnosis. This report creates a profile of the cancer’s traits, including its size and location, and it describes features that provide clues to the aggressiveness of the tumor.
To create the pathology report for your biopsy, a pathologist, a doctor who diagnoses cancer by looking at cells and tissues under a microscope, looks at tissues collected during your initial procedure. The pathology report for your biopsy will provide much of the information for your treatment, but more details will be added once you have your definitive surgery. This surgery, which may be a lumpectomy or mastectomy, should end with cancer-free margins: no cancer found along the edges of the tissue removed during surgery. The pathologist will also gather information from your lymph node surgery, if you had one.
You may get your complete report all at once or in parts. You may even get a few reports at a time. Most pathology reports have two or three sections. You may see the sections in this order or differently.
- Gross description: This section describes the tissue the pathologist received as seen with the naked eye. It often includes information on where in the breast the tissue came from and how it was positioned within the breast. It also details how the sample was prepared for the lab to create microscope slides.
- Microscopic description: This section is sometimes called the synoptic summary. It goes into detail about the cancer itself and how it looked under the microscope. The information in this section, and in the next section, is very important in treatment planning.
- Among the details covered in this section of the report are:
- whether the cancer is noninvasive, called in situ, invasive, or both
- if the cancer is invasive, its size
- the number of lymph nodes with cancer, if any
- whether cancer was found in one area or several areas of your breast
- whether the surgeon removed all the cancer, called the margin status
- the growth pattern of the tumor, which shows how the tumor tissue grows and how the cells look under a microscope, called the histologic type and grade (also known as differentiation)
- the pathologic staging
- any predictive or biomarker test results, usually as an additional report
- Final Diagnosis/Impression: This section sums up all the information the doctors learned. It is the true “bottom line” diagnosis.
Make sure to get your own copy of your final pathology report from your surgeon’s office.
The location of the tumor is known as the anatomic site. The word “anatomic” is a medical term that refers to a part of your body: in this case, the part of your body that contains the breast cancer.
Tumors can grow in any part of the breast. If a tumor appears in the breast ducts but is noninvasive, meaning it has not grown beyond the duct and into nearby healthy breast tissues, it is called intraductal carcinoma, ductal carcinoma in situ, or DCIS. You may hear your care team call the cancer any of those three terms, or see them used in place of each other in reports and results.
Cancer cells that start in the ducts or in the lobules, structures that make and carry breast milk to the nipples, become invasive if they have spread outside the ducts or lobules into healthy breast tissues.
Invasive breast cancer can spread to areas outside the breast, such as nearby structures called lymph nodes. Breast cancer can also metastasize or spread to different anatomic sites, including organs and locations outside of the breast and nearby lymph nodes. These areas include the bones, liver, lungs or brain.
The size of an invasive tumor is important for you and your doctors to know as you plan your treatment. Generally, smaller tumors are associated with less intense treatment, better results, and longer survival. Larger tumors are usually treated more aggressively and are associated with shorter survival and higher risk for recurrence, the chance that the cancer will return or spread to other parts of the body.
This isn’t always the case, though. A small cancer can be very aggressive and a large cancer can be very manageable. Your pathology report will include other features of the cancer that will help determine the aggressiveness of your tumor.
Your doctors may be able to get a sense of how large the tumor is during a physical exam or by looking at images from a mammogram or ultrasound. But the only way to know the tumor’s exact size is to measure it after it has been removed during surgery and examined by a pathologist, a doctor who diagnoses cancer by looking at cells and tissues with a microscope.
The pathologist measures the tumor, as seen without a microscope, in three dimensions. He or she will then use a microscope to confirm how much of the tissue sample contains tumor cells. The largest area containing tumor cells is considered the tumor size. For example, a tumor that is 3 centimeters by 2 centimeters by 2 centimeters will be called 3 centimeters in size, once confirmed by microscope.
Your pathology report will include the histologic grade of the tumor. Your pathologist will assign the histologic grade, also called differentiation, based on how different the tumor and its cells look from healthy breast tissue and its cells, and how many cells are actively dividing.
Invasive cancer can be either:
- Well differentiated, which means it looks similar to healthy tissue and healthy cells. These cancer cells tend to grow and spread more slowly.
- Moderately differentiated, which means the tumor tissue and tumor cells look somewhat different from healthy tissue and healthy cells, but not completely different.
- Poorly differentiated, which means they look very different from healthy tissue and healthy cells. These cancer cells tend to grow and spread more quickly.
Your pathologist will use a grading system to assign the final tumor grade. In breast cancer, the most common grading system is called Nottingham. Your doctor may also call it the Ellston-Ellis system.
The Nottingham system is unique to invasive breast cancer. Your pathologist will score three features of the tumor on a scale of 1 to 3. Features used in the Nottingham system include:
- Tubule, or gland, formation: if the cancer cells group together to make tiny glands called tubules, as healthy breast duct cells do.
- Nuclear grade: how different in size and shape the nucleus of each cancer cell looks compared to the nucleus of other cancer cells and to those of healthy cells. The nucleus of a cell is its center, and contains the cell’s genetic information. When these centers of cancer cells appear in many shapes and sizes, it’s called pleomorphism or pleomorphic.
- Mitotic rate: how many tumor cells in the area are growing and dividing, in a cell process called mitosis.
The pathologist adds together the scores for each of the features above. The total score determines the histologic grade of the tumor.
- A total of 3-5 means the cancer is grade 1. You may see this called low-grade or well-differentiated.
- A total of 6-7 means the cancer is grade 2. You may see this called intermediate-grade or moderately differentiated.
- A total of 8-9 means the cancer is grade 3. You may see this called high-grade or poorly differentiated.
High-grade cancers are often treated differently than low-grade cancers, but that’s not always the case. The cancer grade is only one part of your whole pathology report. Other factors will also impact the treatments available to you. If your pathology report notes you have a high-grade cancer, it’s common to worry about how quickly it can grow and spread. Talk to your doctor about your concerns, what the grade means for you, and how it helps them choose the treatment that is right for you.
The Ki-67 proliferation index, also known as MIB-1, reports what percentage of cells are growing or multiplying. Not all pathologists or labs do this test, so you may not see it on your pathology report. If your pathologist or lab does run this test, you will usually see it as an additional section, called an addendum, to your pathology report. Ki-67 is not used in place of mitotic rate – you should still see the mitotic rate reported as part of the cancers histologic grade.
Ki-67 is a protein made by cells in the process of reproducing, which makes it a good measure of how many cancer cells are growing and multiplying. Invasive tumors with a low percentage of cancer cells making Ki-67 have a low number of cells reproducing. Invasive tumors with a high percentage of cells making Ki-67 have a high number of cells reproducing.
How percentages are measured and what the percentage amount means can vary from lab to lab. How Ki-67 results fit into treatment decisions can be confusing because the information is very complex. Your care team can help you understand what the scores mean and explain each test in terms you understand.
You also may have heard or read that a high Ki-67 proliferation index means the cancer is aggressive or hard to treat. Remember that it’s only one part of many features your care team looks at to decide on treatment.
If you have concerns like these, you can ask your doctor to talk about them.
Lymphovascular invasion happens when cancer cells enter the blood vessels or lymph channels in the breast. Blood vessels carry blood throughout the body, while lymph channels carry lymph fluid throughout the body.
Lymphovascular invasion raises the risk that the cancer has or will spread to other areas of the body, or that it may come back after treatment. At the same time, lymphovascular invasion does not mean that the cancer definitely spread to other areas of your body.
Your pathology report will note if there is lymphovascular invasion or not. Or, your pathology report may not mention lymphovascular invasion at all. If it doesn’t mention lymphovascular invasion, that means your pathologist didn’t see any signs of the cancer spreading into the blood vessels or lymph channels. If you don’t see it in your pathology report and worry the information is missing, it’s OK to ask your care team why it’s not there. It’s always OK to share your concerns and ask questions.
After you were diagnosed with breast cancer, you should have had a number of tests to help your doctors learn more about the cancer and how to treat it. The results of these tests will usually appear as additional sections, called addenda, to your pathology report.
One of those tests checked the cancer’s hormone receptor status. This test checks whether the cancer cells have receptors for the hormones estrogen and progesterone. Receptors on the surface of breast cancer cells work like satellite dishes. They detect and bring in hormone signals. These signals can direct cells to grow, multiply, and repair damage. Learn more about how your doctor tests for hormone receptor status and how it might impact treatment.
Invasive cancers are also tested for another receptor called HER2. These receptors sit on the surface of breast cancer cells and can serve as a target for different cancer medicines. Information about HER2 testing can be complicated. Ask your doctor what your results mean, how they are used to plan your treatment, and any other questions you have.
After you have lumpectomy or mastectomy, information about surgical margins will be added to your pathology report. The surgical margin is the edge of the tissue that was removed. In other words, it is the tissue that the surgeon cut across to remove tissue from your body. Your surgeon’s goal is to remove all of the cancer in your breast and achieve “clear,” or “negative,” margins, meaning they find no cancer at the edge of the tissue they remove. Clear margins are associated with a lower risk of a local recurrence (cancer returning in the same breast). Research shows about 1 out of 4 women who have a lumpectomy go on to have a second breast surgery because the margins weren’t clear after their first surgery.
If you have more than one tumor in the breast, it’s harder to achieve clear margins with a lumpectomy. In this situation, your surgeon may recommend mastectomy instead. Or, your oncologist may recommend neoadjuvant, or pre-surgery, treatment with chemotherapy or targeted therapy, depending on what type of breast cancer you have, to shrink the tumor and make lumpectomy more likely to succeed.
To determine what stage of cancer you have, your surgeon may need to remove lymph nodes under your arm, called axillary nodes, on the side of the body where the cancer was found. Lymph nodes help the body filter out waste, damaged cells, and infection. The axillary lymph nodes are the often the first place breast cancer cells travel to. The first lymph node or nodes to which tumor cells may travel are known as the sentinel nodes.
Knowing whether there are cancer cells in your lymph nodes will help you and your doctors learn the stage of the cancer and decide what treatments you may need in addition to surgery.
Lymph node status is different from lymphovascular invasion (see section above). Lymphovascular invasion means the pathologist saw some cancer cells in the blood vessels or the lymph channels within your breast, rather than in the lymph nodes themselves.
- the size of the tumor, if invasive
- whether lymph nodes near the breast contain breast cancer
- whether the breast cancer has spread from the breast to other parts of the body