Survival impact and toxicity of metformin in head and neck cancer: An analysis of the SEER-Medicare dataset.

Objectives: Recent preclinical research has renewed interest in the interplay between glucose dysregulation and cancer. Metformin holds promise as an adjunctive antineoplastic agent in head and neck cancer (HNC). We aimed to explore the impact of metformin in HNC patients from a population-based dataset.
Patients & Methods: Patients diagnosed with HNC from 2008 to 2011 were identified from the Surveillance, Epidemiology, and End Results (SEER)-Medicare linked dataset and categorized into three groups: non-diabetics (nD), diabetics not taking metformin (DnM), and diabetics taking metformin (D + M). Overall survival (OS) and cancer-specific survival (CSS) were compared between groups using Kaplan-Meier and Cox regression controlling for sociodemographic, clinical, and treatment covariates. The incidence of toxicities associated with HNC therapy was compared among groups using χ ² analysis.
Results: Among 1646 patients, there were 1144 nD, 378 DnM, and 124 D + M. 2-year OS rates was 65.6% for nD, 57.7% for DnM, and 73.4% for D + M by Kaplan-Meier (p < 0.01), and corresponding rates of 2-year CSS were 73.7%, 66.1%, and 88.8% (p < 0.01), respectively. On Cox multivariable analysis, OS among the three groups did not significantly differ; however, CSS was significantly worse among both nD versus DnM as compared to D + M. Toxicity rates were not significantly increased among D + M.
Conclusion: HNC patients with diabetes taking metformin experience improved CSS. Prospective investigation of the addition of metformin to standard-of-care HNC therapy is warranted.
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