A breast cancer diagnosis is unwelcome news, but thanks to the relentless efforts of researchers and support from individuals and advocacy groups, the overall five-year survival rate for breast cancer has now reached about 90%. That means 90 out of 100 people with breast cancer are still alive five years after diagnosis, according to the American Cancer Society.

The stage of cancer at diagnosis and the patient’s overall health are essential factors in overcoming the disease, along with the available treatment options. There are many different breast cancer treatments, and hormone therapy may be recommended.

The Cleveland Clinic states that hormone therapy can treat hormone receptor-positive (HR+) breast cancer, including the most common subtype: estrogen receptor-positive (ER+) breast cancer. Estrogen is one of the two hormones (along with progesterone) produced in the ovaries for much of a woman’s life. After menopause, estrogen levels decrease, and estrogen is produced in body fat and muscle, according to Cancer Research UK. Estrogen and progesterone may promote the growth of some breast cancer cells.

Hormone receptor status in breast cancer is determined by analyzing tumor tissue through biopsy or surgery to detect estrogen and progesterone receptors. This process is known as immunohistochemistry. According to Penn Medicine, if at least 1% of the tested cells show these receptors, the cancer is classified as hormone-positive. If the tumor responds to progesterone, it is labeled PR+. Do not confuse HR+ and PR+ with Human Epidermal Growth Factor Receptor 2 (HER2) cancers, as HER2 cancers involve a protein that controls cell growth, not hormones that influence the cancer cells.

Hormone therapy may be used for specific reasons, according to the Mayo Clinic. It can shrink a cancer before surgery. It may also slow or stop the growth of cancer that has spread (metastatic cancer). Hormone therapy might also decrease the risk of cancer developing in other breast tissue. Sometimes, doctors use hormone therapy after surgery to lower the chance of recurrence.

Hormone therapy for breast cancer may include aromatase inhibitors, selective estrogen receptor modulators, or estrogen receptor downregulators. Side effects of these treatments can include fatigue, mood swings, nausea and vomiting, tender or swollen breasts, decreased interest in sex, hot flashes, and joint and muscle pain or stiffness, according to the Cleveland Clinic. By working together, patients and doctors can review the risks and benefits of hormone therapy to decide what is best for the cancer and the prognosis after treatment. Learn more at www.cancer.org.