How long should adjuvant tamoxifen be continued?

Tamoxifen can reduce the risk of relapse and death from breast cancer when used as adjuvant therapy for early stage breast cancer. While most trials have tested 1 or 2 years of therapy, it is now common to continue tamoxifen for 5 or more years. However, the optimal duration remains controversial. The complex physiologic and clinical effects of tamoxifen cannot be fully predicted by our rudimentary understanding of its basic mechanisms of action. An analysis of randomized clinical trials comparing different tamoxifen durations is therefore necessary. Individual patients' risks of breast cancer recurrence, other beneficial effects, and potential toxicities also must be entered into the decision-making process.