Hormone therapy is not a first-line cancer treatment, but it is often used in combination with other cancer treatments. It’s used to treat cancers that are dependent on hormones to grow and spread. People receiving hormone therapy either take medications or undergo surgery to reduce the levels of certain hormones (e.g., estrogen, testosterone) involved in cancer growth. Hormone therapy can be used to treat cancer of the breast, ovaries, uterus and prostate. Hormone therapy’s side effects can include temporary or permanent infertility. Some more advanced cancers can develop resistance to hormone therapy and begin to grow again after a period of time. In this case, your oncologist may need to switch you to a non-hormonal therapy.