Breast cancer begins when abnormal cancerous cells in the breast grow and multiply without stopping, creating a tumor. It usually starts in the ducts or lobules of the breast.
Advanced breast cancer includes the most serious of the 5 possible stages, Stages III and IV. Stage III is locally advanced breast cancer, which means the cancer has spread to lymph nodes and/or other tissue in the breast, but not to further sites in the body. Stage IV is metastatic breast cancer. At this stage, the cancer has spread to other sites of the body, such as the liver, lungs, bones, brain, and/or others. There are many types of advanced breast cancer, with the most common type being hormone receptor-positive (HR+).
Given these various and sometimes inconsistent terms, if you or a loved one is diagnosed with advanced or metastatic breast cancer, it is important to discuss with your doctor specifically what stage it is, as well as its other characteristics, such as hormone receptor status and where the cancer has spread. These can be important for making treatment decisions.
Treatment of HR+ breast cancer
HR+ breast cancer is characterized by hormone receptor-positive tumors, a group of cancers that express receptors for certain hormones, such as estrogen and progesterone. Cancer cell growth can be driven by these hormones.1 HR+/HER2- breast cancer, also called Luminal A, is the most common type of breast cancer.2 HR+ cancer is usually treated with hormone therapies, also called endocrine therapies, that help stop tumor growth first. These therapies help prevent the cancer cells from getting the estrogen they need to grow.3 HR+ breast cancer tumors have a slightly lower chance of coming back in the first 5 years after diagnosis than HR- breast cancer tumors. Sometimes, however, the cancer becomes resistant to hormonal therapy and the treatment stops working.3
While hormonal therapy, also called endocrine therapy, remains the cornerstone of treatment for women with HR+ breast cancer, most women will eventually develop treatment resistance.4 Therapeutic resistance has sometimes been associated with overactivation of the PI3K/mTOR pathway.4 In HR+ advanced breast cancer, there may be other drugs that can be combined with hormonal therapy. These combination drugs work to block certain protein cells.
Questions to ask your doctor
Check out the Make Your Dialogue Count questionnaire to create a personalized discussion guide to help you have better discussions with your health care team about living with advanced breast cancer.
Visit AdvancedBreastCancerCommunity.org, a hub of resources, support, and education tailored specifically for people living with advanced or metastatic breast cancer, as well as their supporters, caregivers, and loved ones.