Association of CYP2D6 and CYP2C19 polymorphisms and disease-free survival of Thai post-menopausal breast cancer patients who received adjuvant tamoxifen

Montri Chamnanphon; Khunthong Pechatanan; Ekapob Sirachainan; Narumol Trachu; Wasun Chantratita; Ekawat Pasomsub; Wilai Noonpakdee; Insee Sensorn; Chonlaphat Sukasem

doi:10.2147/PGPM.S42330

Association of CYP2D6 and CYP2C19 polymorphisms and disease-free survival of Thai post-menopausal breast cancer patients who received adjuvant tamoxifen

Pharmgenomics Pers Med. 2013 May 24:6:37-48. doi: 10.2147/PGPM.S42330. Print 2013.

Authors

Montri Chamnanphon¹, Khunthong Pechatanan, Ekapob Sirachainan, Narumol Trachu, Wasun Chantratita, Ekawat Pasomsub, Wilai Noonpakdee, Insee Sensorn, Chonlaphat Sukasem

Affiliation

¹ Division of Pharmacogenomics and Personalized Medicine, Department of Pathology, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Bangkok, Thailand.

Abstract

Purpose: To investigate the impact of CYP2D6 and CYP2C19 polymorphisms in predicting tamoxifen efficacy and clinical outcomes in Thai breast cancer patients.

Methods: Polymorphisms of CYP2D6 and CYP2C19 were genotyped by the AmpliChip™ CYP450 Test (Roche Molecular Diagnostics, Branchburg, NJ, USA) for 57 patients, who were matched as recurrent versus non-recurrent breast cancers (n = 33 versus n = 24, respectively, with a 5-year follow-up).

Results: Based on the genotype data, five CYP2D6 predicted phenotype groups were identified in this study including homozygous extensive metabolizer (13 of 57, 22.80%), extensive/intermediate metabolizer (23 of 57, 40.40%), extensive/poor metabolizer (3 of 57, 5.30%), homozygous intermediate metabolizer (14 of 57, 24.50%), and intermediate/poor metabolizer (4 of 57, 7.00%), and three CYP2C19 genotype groups including homozygous extensive metabolizer (27 of 57, 47.40%), extensive/intermediate metabolizer (27 of 57, 47.40%), and homozygous poor metabolizer (3 of 57, 5.30%). The CYP2D6 variant alleles were *10 (52 of 114, 45.60%), *5 (5 of 114, 4.40%), *41 (2 of 114, 1.80%), *4 (1 of 114, 0.90%), and *36 (1 of 114, 0.90%); the CYP2C19 variant alleles were *2 (27 of 114, 23.70%) and *3 (6 of 114, 5.30%). Kaplan-Meier estimates showed significantly shorter disease-free survival in patients with homozygous TT when compared to those with heterozygous CT or homozygous CC at nucleotides 100C>T and 1039C>T (CYP2D6*10) post-menopausal (log-rank test; P = 0.046). They also had increased risk of recurrence, but no statistically significant association was observed (hazard ratio 3.48; 95% confidence interval 0.86-14.07; P = 0.080).

Conclusion: The CYP2D6 and CYP2C19 polymorphisms were not involved in tamoxifen efficacy. However, in the subgroup of post-menopausal women, the polymorphisms in CYP2D6 and CYP2C19 might be useful in predicting tamoxifen efficacy and clinical outcomes in breast cancer patients receiving adjuvant tamoxifen treatment. As the number of breast cancer patients was relatively small in this study, results should be confirmed in a larger group of prospective patients.

Keywords: CYP2C19; CYP2D6; breast cancer; disease-free survival; pharmacogenetics; tamoxifen.