Breast cancer treatment plans are based on both medical and personal choices, however, most factors that help personalize treatment are related to your specific type of breast cancer (the biology of the tumor). This is typically because at the molecular (cell) level, breast cancers differ in many ways. Looking at the genetic makeup of a tumor and profiling it based on its specific genes, also called a prognostic profile, can help doctors provide treatment that will give the most benefit to each patient individually.
It’s critical that your oncologist knows which hormones, if any, are involved in the growth of the breast cancer. They will run some tests that indicate the hormone receptor status and HER2/neu status of the breast cancer tumor. The results then play a large role in the type of breast cancer treatment that’s recommended. There is typically one of the following four results:
Some breast cancer cells are fueled by estrogen and some by progesterone (the naturally occurring hormones in the female body) because of special proteins inside the tumor cells, called hormone receptors. When hormones attach to hormone receptors, the cancer cells grow.
A hormone receptor status is either hormone receptor (HR) positive or hormone receptor (HR) negative.
Hormone receptor-positive breast cancer cells have either estrogen (ER) or progesterone (PR) receptors. These breast cancers can be treated with hormone therapy drugs that lower estrogen levels or block estrogen receptors. HR-positive cancers tend to grow more slowly than those that are HR-negative. HR-positive cancers are generally more common in women after menopause.
Hormone receptor-negative breast cancers do not have estrogen or progesterone receptors. These types of cancers will not benefit from hormone therapy drugs and typically grow faster than HR-positive cancers. HR-negative cancers are more common in women who have not yet gone through menopause.
Some genes and the proteins they make can influence how the breast cancer behaves and also how it may respond to a specific cancer treatment. HER2 is a gene that can play a role in the development of breast cancer.
HER2-negative breast cancers do not have excess HER2. These tumors will not respond to therapies that specifically target HER2 receptors.
HER2-positive breast cancers have too much HER2 protein or extra copies of the HER2 gene. These breast cancers tend to be fast-growing. HER2-positive breast cancer treatment typically includes targeted therapy drugs that slow the growth and kill these cancer cells.
Your pathology report will typically include information about HER2 status and whether or not it is playing a role in your cancer so that your doctor can select a medication that addresses HER2 positive patients.