Comparison of short-term and continuous chemotherapy (mitozantrone) for advanced breast cancer.

132 patients with advanced recurrent breast cancer were treated with four courses of mitozantrone 14 mg/m2 intravenously every 3 weeks (9 weeks). Patients showing disease stabilisation or objective response were randomised to stop chemotherapy or to continue until disease progression. At that stage 27% showed partial responses, 3% complete responses, and 10% disease stabilisation. 22 patients were randomised to continue chemotherapy and 21 to stop. There was no difference in time to disease progression, response duration, or survival between the two groups. Toxicity was mild during the first four courses of therapy. Thus, short courses of single-agent chemotherapy can produce similar therapeutic results to long-term chemotherapy, which has major implications for cost, resource allocation, and toxicity of therapy. Stopping chemotherapy early in responders did not cause rapid relapse. Since drug resistance apparently develops early during therapy, new approaches to modify resistance should be more useful than continuous chemotherapy.