The number of CYP2C8/9 *1/*4/*1/*1 copies was significantly associated with a decreased frequency for axillary lymph node involvement (odds ratio (OR) 0.40; 95% Confidence interval (CI) 0.22–0.74; P=0.003), adjusted for tumour size, histological grade, age at diagnosis, and ER and PR status. The gene discussed is PGR; the disease is neoplasm.