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Does Metformin Reduce Cancer Risks? Methodologic Considerations

  • Diabetes Epidemiology (NM Maruthur, Section Editor)
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Abstract

The substantial burden of cancer and diabetes and the association between the two conditions has been a motivation for researchers to look for targeted strategies that can simultaneously affect both diseases and reduce their overlapping burden. In the absence of randomized clinical trials, researchers have taken advantage of the availability and richness of administrative databases and electronic medical records to investigate the effects of drugs on cancer risk among diabetic individuals. The majority of these studies suggest that metformin could potentially reduce cancer risk. However, the validity of this purported reduction in cancer risk is limited by several methodological flaws either in the study design or in the analysis. Whether metformin use decreases cancer risk relies heavily on the availability of valid data sources with complete information on confounders, accurate assessment of drug use, appropriate study design, and robust analytical techniques. The majority of the observational studies assessing the association between metformin and cancer risk suffer from methodological shortcomings and efforts to address these issues have been incomplete. Future investigations on the association between metformin and cancer risk should clearly address the methodological issues due to confounding by indication, prevalent user bias, and time-related biases. Although the proposed strategies do not guarantee a bias-free estimate for the association between metformin and cancer, they will reduce synthesis of and reporting of erroneous results.

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Acknowledgments

This project was support by the NIDDK-funded Baltimore Diabetes Research Center (P30DK079637).

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Authors and Affiliations

  1. Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA

    Asieh Golozar, Shuiqing Liu & Hsin-Chieh Yeh

  2. Department of Medicine, Johns Hopkins University, Baltimore, MD, USA

    Joeseph A. Lin, Kimberly Peairs & Hsin-Chieh Yeh

  3. The Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University, Baltimore, MD, USA

    Kimberly Peairs & Hsin-Chieh Yeh

  4. Welch Center for Prevention, Epidemiology, and Clinical Research, Johns Hopkins University, 2024 E. Monument St, Suite 2-500, Baltimore, MD, 21205, USA

    Hsin-Chieh Yeh

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  1. Asieh Golozar
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Correspondence to Hsin-Chieh Yeh.

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Asieh Golozar, Shuiqing Liu, Joeseph A. Lin, Kimberly Peairs, Hsin-Chieh Yeh declare that they have no conflict of interest.

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This article does not contain any studies with human or animal subjects performed by any of the authors.

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This article is part of the Topical Collection on Diabetes Epidemiology

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Golozar, A., Liu, S., Lin, J.A. et al. Does Metformin Reduce Cancer Risks? Methodologic Considerations. Curr Diab Rep 16, 4 (2016). https://doi.org/10.1007/s11892-015-0697-z

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  • DOI: https://doi.org/10.1007/s11892-015-0697-z

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