Single Nucleotide Polymorphisms of XRCC1 and the Risk of Head and Neck Cancer

Introduction: Head and Neck Cancers (HNCs)accounts for more than 550,000 cases and 380,000 deaths annually, worldwide. Overall, 57.5% of global HNCs occur in Asia especially in India in both sexes. Single Nucleotide Polymorphisms (SNPs) of DNA repair genes in cancer are the most common form of genetic variations found in the human population. Aim: To draw an association, if any, between polymorphic 347 bp and 445 bp variants of XRCC1 gene and the risk of HNC in a Southern Indian population. Materials and Methods: In the present case-control study, 120 HNC cases were selected from the Department of Radiotherapy, Government General Hospital, Guntur, India. Characteristics were considered for risk assessment in 120 (76 male and 44 female) HNC Cases and XRCC1 gene single nucleotide polymorphisms (SNPs) were analysed in 30 HNC cases (random sampling) and 30 healthy subjects (controls, not habituated to alcohol and/or smoking) to compare the frequency of polymorph variants. DNA was isolated from peripheral blood and after DNA extraction SNPs were genotyped by direct sequencing. Deviations from the Hard-Weinberg Equilibrium (HWE) were tested by using online calculator, chi-square test was used to compare between two variables. Results: In the present study, out of 120 cases, 76 (63.33%) were males and 44 (36.66%) were females. About 72 (60%) cases of males had the habit of smoking and only 7 (15.91%) cases of females were smokers. Among male cases alone, 75.50% constitute smokers. A total of 57 cases, consisting of 18 (23.68%) males and majority of females 39 (88.63%) responded that they never consumed alcohol. In the present study, data showed no significant allelic associations for SNP of XRCC1 347bp/445bp and HNC. Conclusion: The present study confirms the principle role of cigarette smoking and alcohol consumption in HNC. This is significant and positive interaction between these two factors. The frequency of heterozygous genotype (A/G) of XRCC1 gene in both cases and controls showed no significant difference and hence, There was no association between them. In addition, further studies are required for evaluating the effect of gene to gene and gene to environment interactions on these gene polymorphisms with HNC susceptibility, in Indian population.