Duration of therapy in adjuvant chemotherapy trials.

Almost all the adjuvant chemotherapy regimens that have been established as effective in prolonging the survival of patients with early breast cancer have been administered for 1 to 2 years. If equally effective, shorter courses of therapy would result in less overall toxicity and allow early introduction of non-cross-resistant regimens. The efficacy of 2 regimens differing only in duration was compared in 5 randomized trials that have been conducted. None have shown an overall survival advantage for a longer course of therapy, and only 1 has shown an advantage in time to recurrence for a longer course. There has been a nonsignificant trend in some of the trials in favor of the shorter arms of therapy. It must be concluded at the present time that regimens that utilize 4 to 6 months of therapy are likely to be as effective and are probably preferable to 12 or more months of therapy.