When pCR was achieved with trastuzumab and pertuzumab in patients presenting with cN0, HER2-positive cancer, 67% would favor giving trastuzumab alone as adjuvant treatment, and 21% would agree to consider pertuzumab and trastuzumab if patients had baseline stage 1 or 2 and 12% would give both agents with baseline stage 2 only. This evidence concerns the gene ERBB2 and cancer.