Megace, known scientifically as megestrol acetate, is a medication that belongs to the class of drugs known as progestins. It's used primarily for stimulating appetite in patients who have AIDS and experience significant, unexplained weight loss. Besides its role in appetite stimulation, Megace is also used in the treatment of advanced breast cancer and endometrial cancer. Its mechanism of action involves altering hormone balances in the body, which can help in stopping the growth of certain types of cancer cells and improving appetite.