Impact of CYP2D6 polymorphisms in tamoxifen adjuvant breast cancer treatment

T. Ramón Y Cajal, A. Altés, L. Paré, E. Del Rio, C. Alonso, A. Barnadas, M. Baiget

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68 Citations (Scopus)


The aim of this study is to evaluate the impact of CYP2D6 genotyping in predicting disease-free survival and toxicity in breast cancer patients treated with adjuvant tamoxifen. DNA from 91 patients was genotyped using the AmpliChip CYP450 GeneChip®, Roche that facilitates the classification of individuals by testing 27 alleles. When patients were grouped into group 1 (*4/*4,*4/*41,*1/*5 and*2/*5) and group 2 (the remaining genotypes), a significant difference in disease-free survival (DFS) was observed between groups (P = 0.016). The mean DFS in group 1 was 95 months in contrast with 119 months in group 2. No significant relationship was found between the CYP2D6 genotype classification and severe, mild or no toxicity (P = 0.2). Nevertheless, severe, and mild toxicity was more frequent among poor metabolizer patients than in patients with a normal metabolizer pattern (18.8 and 43.8% vs. 10.7 and 36%, respectively). In breast cancer, patients treated with adjuvant tamoxifen, non-functional and severely impaired CYP2D6 variants are associated with a worse DFS and with a higher frequency of severe and mild toxicities. Larger studies of the CYP2D6 genotype-clinical outcomes association are needed to complement initial results. © 2009 Springer Science+Business Media, LLC.
Original languageEnglish
Pages (from-to)33-38
JournalBreast Cancer Research and Treatment
Issue number1
Publication statusPublished - 1 Jan 2010


  • Breast cancer
  • CYP2D6 genotype
  • Pharmacogenetics
  • Tamoxifen


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