XPD/ERCC2 polymorphisms and risk of head and neck cancer: a case-control analysis

DNA repair capacity is central in maintaining normal cellular functions, Va riants of several DNA repair genes,including the nucleotide excision repair gene XPD, have been described recently, Because we previously reported tha t patients with squamous cell carcinoma of the head and neck (SCCHN) had lo wer DNA repair capacity than healthy controls, we hypothesized that inherit ed polymorphisms of XPD may contribute to genetic susceptibility to SCCHN, a tobacco-related cancer. To test this hypothesis, we conducted a hospital- based case-control study of 189 SCCHN patients and 496 cancer-free controls who were frequency-matched on age, gender and smoking status, All subjects were non-Hispanic whites. Two XPD polymorphisms (C22541A and A35931C) were typed using the restriction enzymes TftI and PstI, respectively. Multivari ate logistic regression analysis was performed to calculate adjusted odds r atios (ORs) and 95% confidence intervals (CIs). In the controls, the freque ncies of the variant 22541A and 35931C alleles were 44.7% and 33,8%, respec tively. The frequency of the 22541A homozygous genotype (22541AA) was lower in cases (15.9%) than in controls (20,4%) but was not associated with risk (adjusted OR = 0.90; 95% CI = 0.52-1.56) for SCCHN, The frequency of the 3 5931C homozygous genotype (35931CC) was higher in cases (16.4%) than in con trols (11.5%) and associated with a borderline increased risk (adjusted OR = 1.55; 95% CI = 0.96-2.52) for SCCHN, The risk was higher in older subject s (OR = 2.22; 95% CI = 1,03-4,80), current smokers (OR = 1.83; 95% CI = 0.7 9-4.27) and current drinkers (OR = 2.59; 95% CI = 1.25-5.34) in the stratif ication analysis. These results suggest a gene-environment interaction, but this did not reach statistical significance. The findings are limited due to the relatively small numbers in the subgroups and need to be verified by further investigations.