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You may already know this from the biopsy but again, this will confirm whether it is a duct cell cancer, lobular cancer, tubular or even1 in situ cancer ―DCIS. It will also give you the definitive size. Again, there may be many sizes on the path report such as the size of the lump that is removed but the only size that is really important is the size of the invasive component.

We do not really care about the size of the in situ component whether it is 1 cm or 10 cm makes no difference. However, we do need to know the size of the invasive component. The next factor to look at is the grade of the tumor.

The pathologist determines the grade based on different criteria such as how fast the cancer is growing and whether the cancer forms tubules. This is not important but it is important to know if your cancer is grade one, which generally means it is less aggressive, grade 2 is medium aggressiveness and grade three is a more aggressive cancer. The grade is one of the criteria used by the medical oncologist when recommending treatment. The next important section is the margins of the tumor.

I spent time discussing this in the surgery section but it is important to know that all of the cancer was microscopically removed. We want at least a 3 mm. Other physicians would say 1mm, I would use 3mm but preferably 5 mm margins. Again, a margin is the gap between all the sides of the tumor and normal breast tissue. Pathologists will give the distance in mm or cm. If the margins are not clear, they will say the margin is involved or they may say the cancer is approaching the margin or maybe less than one millimeter. This will mean additional surgery to ensure all the cancer has been removed and, in some cases, may mean a mastectomy. If for some reason the margins are closely involved but additional surgery cannot be performed then radiation may be needed as there is always a chance spare cells may have been left. The one margin that is tough to deal with is the back or the posterior margin because it backs up to the muscle of the chest wall called the pectoralis muscle. The surgeon will remove as much of the cancer as possible without removing the muscle but if the cancer is at the pectoralis muscle you may need radiation.

It also contributes to determining the stage of the breast cancer. On the lymph node section of the pathology report the total of nodes removed will be listed as well as the total number of nodes involved with cancer. How the cancer is involved with lymph nodes is divided into three ways: macroscopic, microscopic, and Immunohistochemical positive ―I (+). This is confusing and we will go over it in detail. It should also be remembered the number of lymph nodes removed will be different among patients. Patients who only have a sentinel lymph node removed may only have one or two lymph nodes examined. However patients who have cancer involving the sentinel lymph node will have additional lymph nodes removed either at the time of surgery or with an additional surgery. The surgeon does not always know how many lymph nodes they are removing as the lymph nodes can be close to the breast tissue and may be removed as part of the breast tissue. Patients tell me, “They only removed one lymph node”. Well, the pathology report says they removed 6 lymph nodes. Again, the pathology report is the bible and the final proof. Let’s look at the sizes of the cancer in the lymph nodes. If there is macroscopic involvement of cancer in the lymph nodes that means the cancer in the lymph nodes is greater than 0.2 cm. Microscopic means the cancer can only be seen by the microscope and is less than 0.2 cm.

The next part is confusing and I hesitate to discuss it but you will see it in the pathology report and I really want you to understand what it means. So read this carefully. The lymph nodes if negative will be read as negative i+ or negative i-. The “i” means Immunohistochemical. If there is macro or microscopic disease in the lymph node, the Immunohistochemical feature is not used. However pathologists on all negative lymph nodes meaning they cannot see any cancer even within the microscope will put a special chemical on the lymph nodes which will highlight any single or clusters of cells in the lymph node.

The problem is we do not know what those highlighted cells mean. They could be small cancer cells that have moved from the breast to the lymph node or just normal cells that have just moved from the breast to the lymph nodes from manipulation of the breast during biopsy or surgery. However, even if highlighted cells are found, the lymph node is still considered a negative or not involved lymph node in the staging system. It will be classified as N0 (i + or -). Most oncologists look at this information but do not put a great deal of emphasis of this stain. So the question may arise—why is it even checked? Well that is a good question and no one really has an answer. Any person who can tell you exactly what these cells mean – run, they have no clue what they are talking about! In the reference pathology report shown, the “i” status (see I Status) is shown with the stage.

3Cancer cells may have receptors or almost like little baseball cups of the cell’s surface. These are referred to as estrogen and progesterone receptors. When they are present it is referred to as positive. That means the breast cancer cells are fed by the female hormones estrogen and progesterone. This is a good thing. We want this. It is good for two reasons. Breast cancer cells which are fed by estrogen and progesterone tend to be less aggressive and also make a patient a candidate for the anti-hormonal pills. These pills commonly referred to as hormonal therapy and include names such as tamoxifen, Arimidex, or Femara. So it is not only a better acting breast cancer but it also gives the oncologist another option for treatment, meaning systemic treatment, because these pills go throughout the whole body. Cancer cells which do not have these hormone receptors meaning “negative” tend to be much more aggressive and do not respond to any of the pills.

The last major part of the pathology report will also be reported near the hormone receptor section of the report.

This stands for human epidermal receptor 2. I am just going to refer to this as HER2. HER2 is a protein on about 20% of the breast cancer cells and makes the cancer more aggressive. On the pathology report HER2 will be reported by how intensely it stains on the cancer cells. A pathologist can put stains on the cancer cells and determine how intense they are. If they report the stain as 0 or 1+, this is negative or no HER2. If the HER2 stain is reported as 3+ then it is considered positive or yes for HER2. If the stain is 2+ it is considered indeterminate. In these cases a special test called a FISH will be performed to determine if this cancer really is HER2 positive or HER2 negative.

And the HER2 FISH test (see HER2 FISH Test) will be reported as AMPLIFIED which means HER2 positive or NOT AMPLIFIED which is HER2 negative.

It is very important to know the HER2 status of the cancer. As you will see later it has important treatment implications. Cancers which over-express HER2 must be treated with a drug called trastuzumab or Herceptin which neutralizes the HER2 protein. It is an important part of any chemotherapy treatment.

Other findings that you might see on the pathology report include lymphovascular invasion or perineural invasion. Perineural invasion indicates there may be potential invasion around the nerves within the breast. Lymphovascular invasion (see Lymphovascular invasion) suggest the cancer has invaded into the lymphatics (even if it has not reached the lymph nodes) or the blood vessels.