Figure 1.

Forest plot of estimates of breast cancer incidence reduction for the prevention trials. Summary estimate for tamoxifen trials is OR 0.58 (95% CI 0.48-0.71), and for all trials is OR 0.55 (95% CI 0.46-0.66), both with P < 0.001. Heterogeneity tests give >P = 0.07 for all tamoxifen trials, including the NSABP Prevention 1 (P1) study in situ strata, P = 0.04 without this strata, and P = 0.03 for all five strata. In situ cancers are included in the totals, except for P1, for which they are given separately. Data sources are as follows: P1 [3*], RHM study [5*], Italian study [6*] and MORE [7*].