• A drug used to block estrogen and suppress the effects of estrogen and androgens. It is used to treat breast and endometrial cancer, and is being studied in the treatment of other types of cancer. It is also used to improve appetite in patients with cancer. Megestrol belongs to the group of hormones called progestins.
  NCI Dictionary of Cancer Terms
  U.S. National Cancer Institute, 2021
• A progestational hormone used most commonly as the acetate ester. As the acetate, it is more potent than progesterone both as a progestagen and as an ovulation inhibitor. It has also been used in the palliative treatment of breast cancer.
  NLM Medical Subject Headings
  U.S. National Library of Medicine, 2025
• A synthetic derivative of progesterone with antiestrogenic activity. Megestrol binds to and activates nuclear receptors which subsequently bind to and activate target genes for transcription. As an antiestrogen, this agent may inhibit the growth-stimulating effects of estrogen on estrogen-sensitive tumor cells. In addition, megestrol stimulates appetite in cachectic subjects.
  NCI
  U.S. National Cancer Institute, 2021