Effect of anastrozole and tamoxifen as adjuvant treatment for early-stage breast cancer: 100-month analysis of the ATAC trial.

Little data exist on whether efficacy benefits or side-effects persist after 5 years of adjuvant treatment with an aromatase inhibitor. We aimed to study long-term outcomes in the Arimidex, Tamoxifen, Alone or in Combination (ATAC) trial that compares anastrozole with tamoxifen after a median follow-up of 100 months.