The Relationship between Single Nucleotide Polymorphisms of Gene XRCC1 and Toxicity Induced Radiation in Patients with Head and Neck Cancer

Aims: The head and neck cancer is one of the most common types and their treatment brings complications such as dermatitis, mucositis and dysphagia. Studies of genetic variations of patients are those that enable the identification of prognostic factors for treatment, generally based on greater risk of injury to healthy tissue.

Study Design: This study examined the association between single nucleotide polymorphisms (SNPs) of XRCC1 gene in patients with head and neck cancer with adverse reactions presented in normal tissues as result of radiotherapy.

Place and Duration of Study: The study was conduct at Pontifícia Universidade Católica de Goiás, and the patients were recruited at Hospital Araújo Jorge, Associação de Combate ao Câncer em Goiás, Radiotherapy Service.

Methodology: We evaluated 54 patients, through a retrospective study, based on data contained in records and teletherapy records of patients with this cancer who underwent radiotherapy for at least 5 years.

Results: The mean age of patients was 58.43±13.79 years and the mean dose was applied 64,02Gy. Regarding the acute and late toxicities, patients analyzed showed a higher frequency of low-grade morbidities when compared to high grade. For acute toxicity, patients presenting polymorphism rs1799782 had an increased risk for developing mucositis, but the other polymorphisms were not statistically significant for the development of these changes (dermatitis, xerostomia and mucositis) acute. Patients who have studied polymorphisms have no increased risk of developing chronic changes of the larynx and esophagus (P>.05). In relation to the suspension of radiotherapy, patients with polymorphism rs25487 had reduced risk to have treatment discontinued, while patients with polymorphism rs25489 have an increased risk. Conclusion: Studies of genetic variants XRCC1 gene family should continue, to develop mechanisms to determine the degree of radiosensitivity in risk organs in patients with head and neck tumor. Thus, the personalized treatment with ionizing radiation can be prescribed for patients decreasing complications and improving the effectiveness of treatment and quality of life of patients.