Switching to anastrozole versus continued tamoxifen treatment of early breast cancer: Long term results of the Italian Tamoxifen Anastrozole trial

The Italian Tamoxifen Anastrozole (ITA) trial investigated the efficacy of switching to anastrozole for women who were already on adjuvant tamoxifen since 2–3 years. Relapse-free survival (RFS) was the primary end-point; event-free survival (EFS), overall survival (OS) and safety were secondary end-points. Herein, we report an update on the long term results of this trial.At a median follow-up time of 128 months (range14–168 months), 94 events have been recorded in the tamoxifen group compared with 71 events in the anastrozole group (hazard ratio (HR) = 0.71; 95% confidence interval (CI), 0.52–0.97; p = 0.03). RFS was also significantly longer in the anastrozole group (HR = 0.64; 95% CI, 0.44–0.94; p = 0.023); no statistically significant difference between study arms concerning OS was shown, but the trial was not powered enough in respect to this end-point. The incidence of serious adverse events (SAE) like bone fractures was comparable (four in each arm), while gynaecological problems were still significantly more numerous among the women continued on tamoxifen (21 patients developed a SAE in this group, including eight endometrial cancers, compared to three patients who suffered from a SAE, including one endometrial cancer, in the anastrozole group: p < 0.000).Present data confirm that switch is safe and can provide long-term gain in terms both of RFS and of EFS, which persists even several years since treatment discontinuation.