Megestrol is a man-made progestin similar to the hormone progesterone. Experts do not completely understand how megestrol works. But most believe that it interferes with receptors that help breast cancer grow and spread.
Stebbing J, Ngan S (2010). Breast cancer (metastatic), search date June 2009. Online version of BMJ Clinical Evidence: http://www.clinicalevidence.com.
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