Knowing as much as you can about your cancer can help you decide what treatment may be best for you.
There are many types of breast cancers. They are named after where they start, if they spread and how they grow.
The three main groups of breast cancer are:
- Ductal carcinoma in situ (DCIS). This mean cancer (carcinoma) in the ducts of the breast. The cancer hasn’t spread out of the ducts and is still in place (in situ). The ducts are the tubes that carry milk in the breast when a woman is breast feeding.
- Invasive ductal carcinoma (IDC). This is the most common type of breast cancer. The name means that the cancer cells have spread out of the ducts into the breast tissue around the ducts.
- Invasive lobular carcinoma (ILC). This is like IDC except the cancer started in the cells (lobules) where the milk is made (milk glands).
Doctors can get more information by studying your cancer cells. They look under a microscope and run tests to find clues for what might be causing your cancer. These are called biomarkers. For example, doctors might test to see if certain hormones help the cancers grow. They can also see what shape the cancer cells are and where they came from.
Doctors compare your cancer cells to your healthy breast cells. That helps the doctors know what grade your cancer is in. Grade 1 cells look the most like normal breast cells and usually grow the slowest. Grade 3 cells look the most different than normal breast cells and usually grow the fastest. Staging is also done to see how far the cancer has spread.
Cancer cells are tested to see if they use certain hormones (estrogen or progesterone) to help them grow. Cancer cells that are estrogen-positive, for example, need estrogen to help them grow. Cancer cells that are progesterone-positive need progesterone to help them grow. The best treatment for these cancers is medications that block these hormones from working.
The doctors may also look for certain proteins in the cancer cells, like human epidermal growth factor receptor 2 (HER2), that help cancers grow. If someone is HER2-positive, they would probably do best with therapy that shuts down HER2.
Some tumors aren’t hormone-positive or HER2-positive. These can be the hardest to treat. But as more biomarkers are discovered, doctors can prescribe more precise cancer treatments.