Metformin for Oral Cancer Prevention

Inclusion Criteria: Participants with oral leukoplakia or erythroplakia with mild, moderate, or severe histologic dysplasia, or hyperplasia not associated with mechanical factors such as ill-fitted dentures Measurable disease - minimum lesion size of 8 x 3 mm before initial biopsy Karnofsky performance status >= 70% Leukocytes >= 3,000/microliter Absolute neutrophil count >= 1,000/microliter Platelets >= 100,000/microliter Total bilirubin =< 1.5 × institutional upper limit of normal (ULN) Aspartate aminotransferase (AST) (serum glutamic oxaloacetic transaminase [SGOT])/alanine aminotransferase (ALT) (serum glutamate pyruvate transaminase [SGPT]) =<1.5 × institutional ULN eGFR > 40 mL/min using the Cockcroft-Gault equation Life expectancy > 3 months Willing to use adequate contraception (barrier method, abstinence, subject has had a vasectomy or partner is using effective birth control or is postmenopausal) for the duration of study participation Ability to take oral medication Ability to understand and the willingness to sign a written informed consent document Exclusion Criteria: Patients with diabetes who are taking insulin or oral agents History of diabetic ketoacidosis Participants may not be receiving any other investigational agents within past 3 months History of allergic reactions attributed to compounds of similar chemical composition to metformin or prior use of metformin within the last year Uncontrolled intercurrent illness including, but not limited to, ongoing or active infection, human immunodeficiency virus (HIV)-positive, symptomatic congestive heart failure, unstable angina pectoris, cardiac arrhythmia, or psychiatric illness/social situations that would limit compliance with study requirements Oral carcinoma in situ History of chronic alcohol use or abuse defined as any one of the following: a) average consumption of 3 or more alcohol containing beverages daily in the past 12 months; b) consumption of 7 or more alcoholic beverages within a 24 hour period in the past 12 months Glycated hemoglobin (HbA1c) > 8% Pregnancy or nursing women Acute or chronic liver disease, evidence of hepatitis (infectious or autoimmune), cirrhosis or portal hypertension History of renal disease History of prior head and neck squamous cell carcinoma (HNSCC) unless curatively treated for >= 1 year Have received chemotherapy and/or radiation for any malignancy (excluding non-melanoma skin cancer and cancers confined to organs with removal as only treatment) in the past 2 years; ongoing adjuvant hormonal therapy for breast cancer is allowed ]]>