Results of the extended follow-up of patients in the NCCTG 89-30-52 trial presented at the San Antonio Breast Cancer Symposium in 2008, expanded the allele coverage to include the CYP2D6*3, *5, *10, *17, and *41 alleles and confirmed that PM (defined as patients with two null alleles or any patient administered a potent inhibitor) had a statistically significantly higher risk of relapse [22]. The gene discussed is CYP2D6; the disease is breast cancer.