In patients with node-positive or high-risk node-negative operable HER2-positive breast cancer, the APHINITY trial found that the addition of pertuzumab improved the 3-year rate of invasive disease-free survival (iDFS) from 93.2% in the placebo group to 94.1% in the pertuzumab group (HR 0.81; 95% CI 0.66–1.00, P = 0.045). This evidence concerns the gene ERBB2 and breast cancer.