ABSTRACT
OBJECTIVE: To evaluate polymorphism frequency of the CYP2D6*4, *10, and * 17 alleles in women with breast cancer treated with tamoxifen. MATERIALS AND METHODS: Ninety-five women with estrogen and progesterone receptor-positive breast carcinoma were investigated from September to December 2013. A three-ml sample of peripheral blood was collected from each patient to analyze the presence of CYP2D6 *4, *10, and *17 allele polymorphism by specific polymerase chain reaction technique (PCR) for analysis of haplotypes *1, *4, *10, and *17, determined by studies of different single-nucleotide polymorphism (SNP). The data obtained were compiled and analyzed with the aid of Excel software 2010. RESULTS: The frequency of CYP2D6 alleles *4, *10, and *17 was 16%, 29%, and 2%, respectively, and haplotype * 1/*10 was shown in 22% of the women. The phenotype of intermediate metabolism occurred in 8% of women. CONCLUSIONS: The present study showed a deficiency in tamoxifen metabolism, characterized by intermediate metabolism in 8% of Brazilian women.