A clinical trial of megestrol acetate in advanced breast cancer

Megestrol acetate is a potent oral progestin with anti-estrogenic activity. It was given in doses of 40-mg tablets after each meal and at bedtime (160 mg daily) to 30 patients with progressing disseminated breast cancer. It was well tolerated; no toxic reactions were observed. Seven patients < 23.3%) met the criteria of improvement as employed by the Cooperative Breast Cancer Group, and had a mean objective remission of 5.5 months. Most of the seven responders to megestrol acetate had prior trials with a sex hormone, and one or more cytotoxic compounds; three had a modified Cooper's five-drug combination. The circumstance that this progestin has demonstrated utility late in the sequence of therapy bodes well for this compound having a useful role in the treatment of advanced breast cancer.