Significance of XRCC1 Codon399 Polymorphisms in Chinese Patients with Locally Advanced Nasopharyngeal Carcinoma Treated with Radiation Therapy

Aim: Little is known about the relationship between XRCC1 Codon399 polymorphisms and radiotherapy (RT) outcomes in patients with nasopharyngeal carcinoma (NPC). We aimed to investigate whether XRCC1 Codon399 polymorphisms were correlated to treatment efficacy and normal tissue toxicity in Chinese patients with locally advanced NPC after RT.

Methods: Sixty eligible patients with NPC stage III-IVa were recruited. Patients received definitive RT, 66-76 Gy. One cycle neoadjuvant chemotherapy with docetaxel and cisplatin regimen was used before RT, two or three cycles for concurrent chemo-RT followed by two to four cycles adjuvant chemotherapy with the same regimen. Before the treatment, XRCC1 Codon399 polymorphisms were determined by polymerase chain reaction based ligase detection reaction methods.

Results: Six of 60 NPC patients were homozygous for XRCC1 Codon399 Gln/Gln and 35% were heterozygous. The expressions of genotypes were unrelated to gender, age, clinical stage, T stage or N stage. Codon399 Gln/Gln allele correlated with a higher medium-term tumor regression ratio after RT for primary nasopharyngeal neoplasm and metastatic lymph nodes (>80% vs 40-60%, P < 0.01). Compared with other two genotypes, patients with XRCC1 Codon399 Gln/Gln allele were more likely to obtain complete remission of tumor (100% vs 76 and 67%, P > 0.05). No correlation between XRCC1 Codon399 polymorphisms and acute or late radiation-induced injury of normal tissues was observed.

Conclusions: The XRCC1 Codon399 Gln/Gln allele may be associated with better tumor regression, and is suggested as a promising predictive factor for outcome for locally advanced NPC. Further study with larger samples and long-time follow-up is needed for accurate assessment.