Randomized clinical trial of megestrol acetate versus tamoxifen in paramenopausal or castrated women with advanced breast cancer.

Fifty-five women with progressive metastatic breast cancer who were paramenopausal (1 to less than 5 years since last menstrual period) or castrated were randomized to receive either megestrol acetate (150 mg/m2 daily in three divided doses) or tamoxifen (10 mg twice daily). The regression rate (complete plus partial) was higher for tamoxifen (26%) than for megestrol acetate (14%), but not significantly so. Analysis of time to treatment failure showed no significant difference (medians: megestrol acetate, 65 days; tamoxifen, 58 days). There was survival advantage associated with megestrol acetate (P = 0.02 after adjustment for stratification factors) that is difficult to interpret given the results of analysis of regression and time to treatment failure for the two agents.