While there is no one specific cause for many cancers, there are variables that increase the risk of developing certain cancers. Hormones are risk factors for several cancers, including prostate, breast and endometrial cancer. For some cancers, treatment options include medications to alter hormone levels and slow down cancer growth.
Prostate Cancer
Male hormones, called androgens, are produced in the testicles and fuel the growth of prostate cancer cells, according to the American Cancer Society. By reducing levels of androgens in the body, prostate cancer growth can be slowed and tumors may shrink. While hormone therapy does not cure prostate cancer, it is often used in treating the disease, especially when you are not able to have surgery or radiation or if the cancer has returned after such treatments. Hormone therapy for prostate cancer is also called androgen-deprivation therapy and can consist of removing the testicles or taking medications to prevent the testicles from producing androgens.
Breast Cancer
According to the American Cancer Society, estrogen fuels the growth of two out of three breast cancer types---the breast cancers that are estrogen-receptor (ER) positive and/or progesterone-receptor (PR) positive. This means that estrogen helps these tumors to develop and grow. Even women who are postmenopausal have estrogen in their bodies. Hormone therapy for breast cancer is used to block or reduce estrogen in the body. For breast cancers that are not hormone-receptor positive, hormone therapy is not effective.
Hormone-Replacement Therapy and Cancer
Hormone-replacement therapy (HRT) was commonly used to treat menopausal symptoms in women until 2002, when the Women's Health Initiative study found that HRT caused serious health risks. There are different types of HRT--estrogen-only therapy and combined (estrogen and progesterone) therapy. Estrogen replacement therapy has been found to increase the risk of ovarian cancer if undergone for five or more years, and also increases the risk of endometrial cancer and it is best used in the cases of women without a uterus. Combined hormone-replacement therapy was shown to increase a woman's risk of developing breast cancer and may slightly increase the risk of developing ovarian cancer, although more studies need to be done in this area.
