Patients treated less than what was recommended in St Gallen had cancers in stage 0 (RRR = 21.6, 7.2–64.5), poorly differentiated (RRR = 1.9, 1.2–2.9), HER2 positive (RRR = 3.4, 2.4–4.9) and luminal B-like subtype (RRR = 3.6, 2.6–5.1). The gene discussed is ERBB2; the disease is cancer.