FIG 2.

Kaplan-Meier estimates of (A) cumulative incidence of breast cancer events (invasive breast cancer or ductal carcinoma in situ and of (B) contralateral breast cancer events in the overall intention-to-treat population (ITT) by allocated arm. Numbers in parentheses represent the number of events that occurred within each time interval by treatment arm. The log-rank test was used to draw inferences. The estimate of the hazard ratio (HR) was based on a univariable Cox proportional hazards regression model (ie, with only the treatment arm variable). In the overall ITT population, there were 42 breast cancer events (14 in the tamoxifen arm and 28 in the placebo arm) of which there were 15 contralateral breast cancer events (three in the tamoxifen arm and 12 in the placebo arm). The 3-year cumulative incidence rate of breast cancer events was 2.3% (95% CI, 1.7% to 6.6%) in the tamoxifen arm and 7.6% (95% CI, 4.8% to 11.8%) in the placebo arm, and the 5-year cumulative incidence rate was 6.4% (95% CI, 3.7% to 10.9%) and 11.0% (95% CI, 7.4% to 16.0%), respectively. The 3-year cumulative incidence rate of contralateral breast cancer was 0.4% (95% CI, 0.1% to 3.1%) in the tamoxifen arm and 2.5% (95% CI, 5.5% to 1.1%) in the placebo arm, and the 5-year cumulative incidence rate was 1.1% (95% CI, 0.3% to 4.5%) and 4.2% (95% CI, 2.2% to 8.0%), respectively.