New research indicates that for women with HER2-positive, operable breast cancer, pertuzumab increased the rates of invasive-disease–free survival when added to trastuzumab and chemotherapy. For the APHINITY study, about 4,800 women with node-positive or high-risk node-negative HER2-positive, operable breast cancer were randomized to receive either pertuzumab or placebo added to standard adjuvant chemotherapy plus 1 year of treatment with trastuzumab. A total of 171 patients (7.1%) in the pertuzumab group had disease recurrence, compared with 210 (8.7%) in the placebo group. According to the data, the estimates of the 3-year rates of invasive-disease-free survival were 94.1% in the pertuzumab arm, compared with 93.2% in the placebo group. Among patients with node-positive disease, the 3-year rate of invasive-disease-free survival was 92.0% in the pertuzumab group and 90.2% in the placebo group, while rates in the cohort of patients with node-negative disease were 97.5% and 98.4%, respectively. Heart failure, cardiac death, and cardiac dysfunction were not frequent in either treatment group. In terms of adverse events, diarrhea was more common in the pertuzumab group than in the placebo group.