Influence Of Cyp2d6 Polymorphism In The Outcome Of Breast Cancer Patients Undergoing Tamoxifen Adjuvant Treatment.

e12521Background: CYP2D6 is the enzyme responsible for the conversion of Tamoxifen (T) to its active metabolites. Genetic polymorphisms of the CYP2D6 gene have been reported as the main cause of variation in the metabolism of T, in fact CYP2D6 gene has more than 100 different allele forms that cover a wide range of activity from ultrarapid to poor metabolizer. Methods: CYP2D6 polymorphism were tested in 87 breast cancer patients undergoing T therapy in the adjuvant setting. We used the activity score system (AS) to translate CYP2D6 genotype into a quantitative measure of phenotype. For each patient, AS value was established as the sum of the value assigned to each allele, 0 (*4, *5), 0.5 (*9, *10, *17, *41), 1 (*1, *2, *35) or 2 (*1xN, *2xN). According to AS value we divided the patients in two groups: Slow Metabolizers (SM) (AS u003c 1.5) (40.2% of the patients) and Rapid Metabolizer (RM) (AS≥1.5) (59.8% of the patients). We evaluated disease free survival (DFS) and Overall Survival (OS) in both groups. Resu...