Lack of association between XRCC1 SNPs and acute radiation-induced injury or prognosis in patients with nasopharyngeal carcinoma

The response to radiation therapy (RT) is closely associated with DNA damage repair. X-ray repair cross-complementing group-1 (XRCC1) is a key gene in the DNA damage repair pathway, and SNPs in this gene alter the expression and activity of its effector protein, which may in turn affect sensitivity to RT. Therefore, the course of tumor treatment and local control rate can be influenced. In the present study, a group of 158 patients with nasopharyngeal carcinoma (NPC) who received intensity-modulated RT at Fujian Cancer Hospital (Fuzhou, China) between July 2012 and October 2013 were included in retrospective chart review and followed up. Plasma was collected before treatment for genotype analysis of the three SNPs of XRCC1, namely Arg194Trp, Arg280His and Arg399Gln. Acute radiation-induced injuries sustained during treatment was graded according to the Radiation Therapy Oncology Group scoring criteria. Post-treatment follow-up was performed until August 2020. In the 158 cases of NPC, no statistically significant association was observed between the three SNPs of the XRCC1 gene and the severity of acute radiation-induced injury or prognosis. However, the AA genotype of XRCC1-Arg399Gln tended to be associated with worse progression-free survival (PFS) compared with the GA + GG genotype, although this was not significant (P=0.069). In addition, multivariate logistic analysis showed that nodal stage was significantly associated with the occurrence of acute severe radiation-induced oral mucositis (P=0.018), and there was also a trend towards an association between nodal stage and the incidence of acute severe radiation-induced pharyngitis; however, this was not statistically significant (P=0.061). Furthermore, multivariate Cox regression analysis showed that older age, distant metastasis and higher clinical stage were independent risk factors for PFS in patients with NPC. In conclusion, relying solely on the aforementioned SNPs of the XRCC1 gene may not provide a robust enough basis to predict the response to RT or prognosis in patients with NPC.