Antihormone therapy is a type of hormone therapy that suppresses selected hormones or their effects, in contrast with hormone replacement therapy, which encourages hormone activity. Antihormone activity is usually achieved by antagonizing their function (with a hormone antagonist) and sometimes by preventing their production. This can be done with drugs, radiation, or even surgery. The suppression of certain hormones can be beneficial to patients with certain cancers, because certain hormones prompt or help the growth of a tumor. This is especially true in cancers relating to the sex organs. Antihormone treatment is thus often specific to sex. For example, androgen deprivation therapy using antiandrogens is important in treating prostate cancer. Breast cancer, which occurs in both women and men but whose disease burden falls mostly on women, also can be treated with antiestrogen therapy. Antiestrogens are not very effective for ovarian cancer.