A Pilot Study of Metformin in Patients With a Diagnosis of Li-Fraumeni Syndrome

Treatment will be administered primarily on an outpatient basis. Patients will be instructed to take 500 mg metformin by mouth 1, 2 or 3 times a day or 1000 mg twice per day depending on dose level. Patients will receive metformin at level 1 dose for 2 weeks. If dose is tolerated, patient will receive level 2 dose for 2 weeks and if tolerated will escalate to level 3 dose, and if tolerated will escalate to level 4 dose. Metformin will be taken for 14 weeks.