Associations between expression levels of nine core nucleotide excision repair genes in lymphocytes and risk of head and neck squamous cell carcinomas in a Chinese population

Background: Head and neck squamous cell carcinomas (HNSCCs) are one of the most common cancers in the world, and nucleotide excision repair (NER) is involved in HNSCCs susceptibility. We investigated whether mRNA expression levels of nine core NER genes were associated with risk of HNSCCs in a Chinese population. Methods: In this study of 251 HNSCC patients and 232 healthy controls, we quantified NER gene mRNA expression levels in cultured peripheral lymphocytes using a quantitative real-time PCR. Results: Compared with the controls, HNSCC patients had statistically significantly lower expression levels of XPA and XPB (P = 0.029 and 0.001, respectively). After dividing the subjects by the controls’ median values of expression levels, we found a dose-dependent association between an increased risk of HNSCCs and low expression levels of XPB (adjusted OR 1.56 and 95% CI 1.07–2.28; P_trend = 0.001). We also identified a significant multiplicative interaction between smoking status as well as alcohol status and mRNA expression levels of XPB (P = 0.014 and 0.042, respectively). Finally, after integrating demographic variables, we found the addition of smoking status and XPB expression levels to the model significantly improved the sensitivity of the expanded model on HNSCC risk. Conclusion: Reduced mRNA expression levels of XPB were associated with an increased risk of HNSCCs in a Chinese population.