Metformin: risk-benefit profile with a focus on cancer

Abstract

Introduction: Epidemiological evidence suggests an increased incidence of cancer in obese, prediabetic, and diabetic patients and a reduced risk of cancer incidence and mortality in diabetic patients on metformin compared with other antidiabetic drugs. In vitro studies support the efficacy of metformin in cancer therapy and prevention. Although metformin seems to be promising as a cancer chemopreventive or therapeutic drug, the principal consideration is whether metformin will be effective in cancer clinical trials for nondiabetic subjects or only in diabetics or subjects with insulin resistance. Safety of metformin is even more important in treating nondiabetic patients.

Areas covered: The present review focuses on epidemiological data and clinical trials testing the efficacy of metformin on cancer, the safety in nondiabetic patients and the future development of this promising drug.

Expert opinion: Meta-analyses of epidemiological in which metformin treatment has been used for diabetic patients show a positive trend for benefit; nevertheless, clinical data outcomes are preliminary and the results of ongoing trials are awaited. The different types of cancer, heterogeneity of populations and presence of comorbidity make it difficult to determine the benefits of metformin in cancer prevention and treatment.

Keywords:

• clinical trials
• metformin
• neoplasm
• safety

Acknowledgements

N Provinciali and M Lazzeroni contributed equally to this work.

Declaration of interest

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

Notes

This box summarizes key points contained in the article.