Hormone therapy, or endocrine therapy, is a non-surgical treatment option for patients who suffer from cancers that use hormones to expand. This type of treatment can be used to treat cancer, to prevent it from reappearing, to slow its growth, and to relieve the patient's symptoms. There are two main types of hormone therapy, one type consists of certain treatments that are meant to block the hormone production, and the other type consists of treatments that make the hormones behave differently. Generally, hormone therapy is used to treat breast, ovarian, kidney, uterine, and prostate cancers.