Association of polymorphism in cytochrome P450 2C9 with susceptibility to head and neck cancer and treatment outcome.

The present case-control study involving 750 cases and equal number of healthy controls investigates the association of polymorphism in cytochrome P450 2C9 (CYP2C9) with head and neck squamous cell carcinoma (HNSCC) and response in patients receiving chemotherapy or combination of radio-chemotherapy. The frequency of heterozygous or homozygous genotypes of CYP2C92 & CYP2C93, which leads to the poor metabolizer (PM) genotype was significantly higher in HNSCC cases when compared to the healthy controls resulting in significantly increased risk in the cases. Tobacco use in the form of tobacco smoking or tobacco chewing was found to increase the risk several fold in cases when compared to the non-tobacco users. Likewise, alcohol intake in cases with variant genotypes of CYP2C92 or CYP2C93 also significantly increased the HNSCC risk in cases when compared to non-alcohol users. Further, majority of the cases carrying variant alleles of both CYP2C92 or CYP2C93 were found to respond poorly to the chemotherapy or combination of radio-chemotherapy. The data suggests a significant association of the CYP2C9 polymorphism with HNSCC and treatment outcome.