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.