Induction of prostate-specific antigen expression by synthetic progestins in patients with prostate and breast cancer.

To the Editor: In the October 1997 issue of the Mayo Clinic Proceedings (pages 932 to 934), Wehbe and associates reported an interesting phenomenon of a patient with prostatic carcinoma whose serum prostatespecific antigen (PSA) level decreased precipitously after discontinuation of megestrol acetate (MA) treatment. The same phenomenon was described previously by Dawson and McLeod. [1] In an effort to explain this phenomenon, Wehbe and coworkers speculated that these prostate cancers may have acquired a mutation in the androgen receptor that results in its activation by nonandrogens, including the synthetic progestin MA. There is no proof or literature supporting the view that an androgen receptor mutation was responsible for the phenomenon observed in these patients, however.