Nineteen of the included studies reported that CYP2D6 genotypes were not associated with survival in breast cancer patients treated with tamoxifen (Refs 16, 24, 29, 30, 43, 44, 47–50, 51, 53, 55, 59, 62, 64, 67, 68, 73). The gene discussed is CYP2D6; the disease is breast carcinoma.