Influence of genetic background and oxidative stress response on risk of mandibular osteoradionecrosis after radiotherapy of head and neck cancer.

ABSTRACT

BACKGROUND: Osteoradionecrosis (ORN) of the mandible is a severe complication of head and neck radiotherapy (RT) treatment, where the impact of individual radiosensitivity has been a suggested explanation. METHODS: A cohort of patients with stage II/III ORN was compared to matched controls. Blood was collected and irradiated in vitro to study the capacity to handle radiation-induced oxidative stress. Patients were also genotyped for 8 single-nucleotide polymorphisms (SNPs) in genes involved in the oxidative stress response. RESULTS: A difference in 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxo-dG) levels was found between the patient cohorts (p = 0.01). The SNP rs1695 in glutathione s-transferase p1 (GSTP1) was also found to be more frequent in the patients with ORN (p = .02). Multivariate analysis of the clinical and biological factors revealed concomitant brachytherapy plus the 2 biomarkers to be significant factors which influense risk of mandibular osteoradionecrosis after radiotherapy of head and neck cancer. CONCLUSION: The current study indicates that oxidative stress response contributes to individual radiosensitivity and healthy tissue damage caused by RT and may be predicted by biomarker analysis.