Evaluation of XRCC1 Gene Polymorphism as a Biomarker in Head and Neck Cancer Patients Undergoing Chemoradiation Therapy.

PURPOSE: We evaluated the correlation of the x-ray repair cross complementing gene 1 (XRCC1) Arg194Trp polymorphism with clinical outcomes in head and neck squamous cell carcinoma (HNSCC) patients treated with concurrent chemoradiation therapy (CCRT).

METHODS AND MATERIALS: In this prospective cohort study, we included 101 patients with HNSCC (oral cavity, pharynx, and larynx) who were aged ≥ 18 years, had stage III to IVB disease, had a Karnofsky Performance Status ≥ 80, and were deemed fit for CCRT. DNA extraction was done through polymerase chain reaction, and the genotypes of XRCC1 polymorphism were detected using designed restriction fragment length polymorphism. The genetic polymorphisms were classified into wild and polymorphic variants (Arg194Trp CT and TT). Radiation therapy was delivered with conventional parallel opposed lateral and low anterior neck fields with concurrent weekly cisplatin, 35 mg/m2 . Acute toxicity was graded per Radiation Therapy Oncology Group criteria, and treatment response was assessed per World Health Organization criteria. Overall survival and progression-free survival (PFS) were estimated using the Kaplan-Meier method.

RESULTS: Of the patients, 62 had the wild type and 39 had polymorphic variants. Patients with polymorphic variants had higher rates of grade > 2 oral mucositis, with 35.8% versus 16.0% (odds ratio [OR], 2.91; 95% confidence interval [CI], 1.13-7.46; P = .023); dermatitis, with 30.7% versus 8.0% (OR, 5.076; 95% CI, 1.62-15.8; P = .003); and laryngeal toxicity, with 25.6% versus 6.4% (OR, 5; 95% CI, 1.44-17.54; P = .006). Complete response rates in polymorphic versus wild variants were 76.9% versus 56.0% (P = .209). At a median follow-up of 21 months, the 2-year PFS and overall survival rates for patients with polymorphic versus wild variants were 57.0% versus 42.2% (P = .077) and 73.0% versus 55.5% (P = .143), respectively.

CONCLUSIONS: Polymorphic variant XRCC1 HNSCC patients treated with CCRT have significantly increased acute radiation morbidities and may have a trend toward better PFS in comparison with the wild variant.