Background: The antioestrogen tamoxifen and progestins act via different receptors and may therefore have complementary effects against human breast cancer. This possibility was tested in a randomized study which compared the effects of tamoxifen, standard-dose megestrol acetate, and these two agents in combination, in patients with metastatic breast cancer.
Patients and methods: 184 post-menopausal patients with metastatic breast cancer were randomized to initial treatment with either tamoxifen (TAM) 40 mg daily, megestrol acetate (MA) 160 mgm daily, or the combination of the two administered simultaneously. Patients crossed over to the alternative single agent on relapse or disease progression. Patients were evaluated for response, time to initial and ultimate treatment failure, and survival.
Results: There were no significant differences between the three groups with respect to response rates, nor the other parameters. Patient survival was significantly associated with age > 60 years, ER positive status, and the absence of visceral metastases.
Conclusions: TAM and MA are both equally effective in response induction as initial treatments and the combination has no advantage. Sequential treatment is still optimal, TAM being the preferred initial agent in view of the reported side effects with MA.