Comparison of antiestrogen and progestogen therapy for initial treatment and consequences of their combination for second-line treatment of recurrent breast cancer.

A randomized clinical trial involving postmenopausal patients with estrogen receptor positive recurrent breast cancer is reported. of 108 patients entered, 166 were evaluable, of whom 79 received oral tamoxifen citrate 10 mg twice daily and 77 oral megestrol acetate 40 mg four times a day. Partial response (PR) plus complete response (CR) rates (both arms, 34%) and time-to-disease progression were similar in both arms. Side effects and toxicity were minimal with both regimens, although more patients who received tamoxifen complained of hot flushes (33% v 11%) and more patients who received megestrol acetate had a 10% or greater weight gain at 6 months from baseline (51% Y 19%). On progression of disease, 73 patients who had achieved a CR, PR, or staMe response received the alternative hormcna I treatment in addition to the original hormonal therapy. Ten of 40 patients (26%) who began treatment with megestrol acetate had a further CR or PR; none of 33 patients originally receiving tamoxifen had a response when megestrol acetate vvas added. Similarfy, patients who received tarruMen as an addiion to their original megestrd acetate treatment also had a significantly longer time to second progression than did those in the comparative arm. It was concluded that as initial hormonal therapy for relapsed patients, either tamoxifen or megestrd acetate can be used with confidence. However, it is suggested that tamoxifen and megestrol acetate should not be used in combination, except for those few occasions when tamoxifen is added as second-line therapy following a completed megestrd acetate response, and the megestrd acetate is continued for its palliative effects on appetite and weight gain. Possible mechanisms behind these results are discussed. 0 1990 by W.B. Saunders Company.