Megestrol acetate (Megace ®). Megestrol acetate is a hormonal therapy drug | most commonly used to treat breast cancer that has spread | . It is also sometimes used to treat womb or prostate cancer. Megestrol can also be used to improve symptoms such as hot flushes or loss of appetite.egestrol acetate (Megace ®). Megestrol acetate is a hormonal therapy drug | most commonly used to treat breast cancer that has spread | . It is also sometimes used to treat womb or prostate cancer. Megestrol can also be used to improve symptoms such as hot flushes or loss of appetite.