Metformin for the Treatment of Recurrent Respiratory Papillomatosis

Objectives: Metformin is an oral agent used for the management of type 2 diabetes. As a result of its ability to alter cellular metabolic requirements, metformin also possesses antiproliferative properties. Metformin has been shown to reduce mutagenesis in several malignancies, however has never been described as a treatment option for recurrent respiratory papillomatosis (RRP). The aim of this study is to present a case series of non-diabetic patients with adult-onset RRP who were treated with metformin. Methods: Case series. Results: Five patients (age 48 +/- 17.82, range 35-68, 4 males, 1 female) were identified with a history of laryngeal RRP who were treated with 500 mg of metformin twice daily. Follow-up time ranged from 11 to 105 months. Two patients had spontaneous regression of RRP lesions within months of starting metformin. Four patients had reduced time intervals between surgical procedures after starting metformin. All patients tolerated metformin well with only minor side effects of self-limiting light-headedness, facial flushing or gastrointestinal upset. Conclusion: Metformin is a low-risk medication that was used to reduce progression and burden of disease in 5 patients with RRP. Further studies should investigate the sole or adjunct use of metformin for treatment of RRP.