Lab tests will be done on the sample of cells that was taken during your breast biopsy. From these tests your doctor will learn if the tumor needs certain hormones to grow. Tumors that need hormones to grow are called hormone-receptor positive (HR+). This is because they have receptors for either estrogen or progesterone.
Another test is done on the biopsy sample to see if the cancer cells produce too much of the growth-promoting protein called the human epidermal growth factor receptor 2, or HER2. Tumors that produce a lot of this protein are known as HER2-positive and tend to grow more quickly. Treatments that target HER2 can be used for these cancers.
There are other tests that can be done on the cancer cells to learn more about the cancer and the types of treatment that may be needed. These results are sent to your doctor as your pathology report. Talk with your doctor about your report and what the information on it means.