Progestin therapy of breast cancer: comparison of agents.

65 postmenopausal women with advanced breast cancer were treated with synthetic oral progestins for 2 months or more. The progestins used were 19-nortestosterone 17-alpha-hydroxyprogesterone derivatives or testosterone derivatives. Objective regression of soft-tissue tumor was noted in 12 of the patients: in 3 out of 19 cases on the 19-nortestosterone derivatives in 5 out of 28 on the 17 alpha-hydroxyprogesterone derivatives and in 4 out of 18 on the testosterone derivative. Of the 65 patients assessed for tumor response on progestins 40 had undergone a previous trial of estrogen or androgen therapy. There was no obvious correlation between tumor response to progestins and response to previous sex hormone therapy. It was possible to differentiate patients with a 29% likelihood of response from those with only a 5% likelihood of response by cytohormonal examination of the postmenopausal vaginal smear before therapy. A total of 72 cases began the therapy; side-effects necessitated stopping therapy in 7 cases all in the 19-nortestosterone and 17-alpha-hydroxyprogesterone groups. Severe nausea and vomiting or abdominal pain accounted for 5 cases; in 1 case the complaint was of severe mental depression and in another irritability. Minor side-effects overcome with persistence included nausea constipation and backache. Only in the 19-nortestosterone group were abnormal changes seen in the aminotransferase levels the first rise appearing after 2 weeks drug administration. It is suggested that the metabolism of different progestins might be investigated in breast cancer patients by the administration of radioactively tagged progestins.