The association of metformin use with keratinocyte carcinoma development in high-risk patients.

Keratinocyte carcinoma (KC) is the most common malignancy in white skinned populations. Metformin one of the most commonly prescribed drugs and has been reported to protect against solid cancers. The association between metformin and KC has not been studied in patients at high risk for a subsequent KC. The purpose of this study is to evaluate the association between metformin and KC development in high-risk patients. We performed a secondary analysis of patients enrolled in the Veterans Affairs Keratinocyte Carcinoma Chemoprevention Trial to compare risk for KC development between metformin users and non-users. Metformin-users compared to non-users had a significantly lower risk for squamous cell carcinoma with an adjusted Hazard ratio (HR): 0.45, (CI: 0.24-0.84, P < .01) and basal cell carcinoma (HR: 0.70, CI: 0.49-0.97, P < .03). Patients at high risk might benefit from metformin use against a subsequent KC.