Effect of Metformin on Progression of Head and Neck Cancers, Occurrence of Second Primary Cancers, and Cause-Specific Survival.

Background. This study aimed to investigate the effect of metformin on progression of head and neck cancers, occurrence of second primary cancers, and cause-specific survival. Methods. This study analyzed a retrospective cohort of 1,151 consecutive patients with head and neck squamous cell carcinoma who were treated at our hospital. Patients were divided into three groups: nondiabetic, nonmetformin, and metformin. Clinical characteristics, recurrence of index head and neck cancer, occurrence of second primary cancer, and survival were compared among the different groups. Results. Of 1,151 patients, 99 (8.6%) were included in the metformin group, 79 (6.8%) were in the nonmetformin group, and 973 (84.5%) were in the nondiabetic group. Diabetic status and metformin exposure had no significant impact on index head and neck cancer recurrence or second primary cancer development (p > .2). The nonmetformin group showed relatively lower overall (p = .017) and cancer-specific (p = .054) survival rates than the other groups in univariate analyses, but these results were not confirmed in multivariate analyses. Conclusion. Metformin use did not show beneficial effects on index tumor progression, second primary cancer occurrence, and cause-specific survival in patients with head and neck cancer compared with nonmetformin users and nondiabetic patients. [ABSTRACT FROM AUTHOR]