An important part of a breast cancer diagnosis is determining what type of breast cancer you have. Knowing the specific type of breast cancer allows your cancer care team to better understand how the tumor may behave and how it may react to different types of treatments. For example, breast cancers that have hormone receptors behave differently than breast cancers that do not. These so-called “hormone receptor positive” breast cancers are treated in part by drugs that impact naturally occurring hormones and/or how these hormones act in the body. Hormone receptor positive breast cancers account for about 80% of breat cancer disagnoses.
How Do Hormones Interact with Breast Cancer Cells?
A hormone receptor is a protein located within various cells in the body, including breast cancer cells, that binds to specific hormones. When a hormone binds to a corresponding receptor in a breast cancer cell, this can trigger cell division and tumor growth.
What Hormones Interact with Breast Cancer Cells?
Estrogen and progesterone are hormones produced and released primarily by the ovaries, with smaller amounts also produced by other tissues (e.g., adrenal glands, fat cells). They are essential for sexual and reproductive development in women. Estrogen facilitates puberty, coordinates menstruation and helps to maintain bone health. Progesterone plays an important role in preparing the body for pregnancy by helping to create an environment conducive to accepting a fertilized egg and promoting the growth of the fetus. However, because of their natural roles in promoting cell growth, the activity of these two hormones can also contribute to the growth of certain types of cancer. In hormone receptor-positive breast cancers, estrogen and progesterone may trigger and promote tumor growth.
Risk of Recurrence Associated with Hormone Receptor Positive Breast Cancer
The behavior of breast cancer cells is unique to the specific type of breast tumor diagnosed, and whether a tumor is classified as hormone receptor-positive or hormone receptor-negative is one factor that will determine each individual’s risk of recurrence after the tumor is removed surgically. To further understand your personal risk of recurrence, your doctor may also order molecular tests to be performed on the original tumor sample.
A noninvasive test called the Breast Cancer Index gives your doctor more information about the behavior of early-stage HR-positive tumors. The results of this test can help you and your doctor decide if extending hormone treatment therapy for an additional five years (after completing the first 5 years of therapy) is likely to benefit you and reduce your risk of recurrence.
If you have been diagnosed with hormone receptor-positive breast cancer and you have questions about your risk of recurrence, talk to your doctor. Your cancer care team can give you information regarding your diagnosis and what your specific type of breast cancer means for your personal risk of recurrence.