Conversely, in women with tumours that were 21 mm or larger, each CYP2C8/9 *1/*4/*1/*1 allele was associated with significantly lower risk for lymph node involvement (OR 0.18, 95% CI 0.06–0.54; P=0.002), while each copy of the CYP2C8/9 *3/*1/*2/*1 allele was associated with a more than doubled risk of lymph node involvement (OR 2.53, 95% CI 0.97–6.64; P=0.06), adjusted for tumour size, histological grade, age at diagnosis, and ER and PR status. The gene discussed is CYP2C8; the disease is neoplasm.