Somatic mutations in the D-loop of mitochondrial DNA in head and neck squamous cell carcinoma.

BACKGROUND The purpose of this study was to characterize somatic mutations in the D-loop of mitochondrial DNA (mtDNA) and their impact on survival in patients with head and neck cancer. METHODS Histologically confirmed head and neck cancer and corresponding noncancerous tissues were obtained from 130 patients. The D-loop of mtDNA sequence in noncancerous tissues was compared with that of paired cancer samples and any sequence differences were identified as somatic mutations. RESULTS Somatic mutations of the D-loop were observed in 81 patients (62.3%) with head and neck squamous cell carcinoma, and most of them occurred in the poly-C tract. There were no significant differences between the mutation group and nonmutation group in demographic and tumor-related features. Patients with D-loop mutations had better survival (4-year disease-specific survival rate: 70.5% vs 50.8%; p = .0435). CONCLUSION Somatic mutation of D-loop of mtDNA was a potential prognostic factor of head and neck squamous cell carcinoma.