Metformin is associated with decreased risk of basal cell carcinoma: A whole-population case-control study from Iceland.

• Published in: Journal of the American Academy of Dermatology
• Main Authors: Adalsteinsson, Jonas A, Muzumdar, Sonal, Waldman, Reid, Wu, Rong, Ratner, Désirée, Feng, Hao, Ungar, Jonathan, Silverberg, Jonathan I, Olafsdottir, Gudridur H, Kristjansson, Arni Kjalar, Tryggvadottir, Laufey, Jonasson, Jon Gunnlaugur
• Other Authors: 1Faculty of Medicine, University of Iceland, Reykjavik, Iceland; Department of Dermatology, University of Connecticut, Farmington, Connecticut. Electronic address: [e-mail]. 2Department of Dermatology, University of Connecticut, Farmington, Connecticut. 3Connecticut Convergence Institute for Translation in Regenerative Engineering, Farmington, Connecticut. 4Department of Dermatology, New York University Langone Health, New York, New York. 5Mount Sinai Department of Dermatology, New York, New York. 6The George Washington University School of Medicine and Health Sciences, Washington, DC. 7Icelandic Cancer Registry, Reykjavik, Iceland. 8Department of Pathology, Landspitali National-University Hospital, Reykjavik, Iceland. 9Faculty of Medicine, University of Iceland, Reykjavik, Iceland; Icelandic Cancer Registry, Reykjavik, Iceland. 10Faculty of Medicine, University of Iceland, Reykjavik, Iceland; Department of Pathology, Landspitali National-University Hospital, Reykjavik, Iceland.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Elsevier 2021
• Subjects: basal cell carcinoma; keratinocyte carcinoma; metformin; squamous cell carcinoma; squamous cell carcinoma in situ; Húðkrabbamein; Carcinoma; Basal Cell; Iceland
• Online Access: http://hdl.handle.net/2336/621894; https://doi.org/10.1016/j.jaad.2021.02.042

To access publisher's full text version of this article click on the hyperlink below Background: Metformin has anticarcinogenic properties and is also known to inhibit the sonic hedgehog pathway, but population-based studies analyzing the potential protective effect for basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) are needed. Objectives: To delineate the association between metformin use and invasive SCC, SCC in situ (SCCis), and BCC. Methods: A population-based case-control study design was employed using all 6880 patients diagnosed in Iceland between 2003-2017 with first-time BCC, SCCis, or invasive SCC, and 69,620 population controls. Multivariate odds ratios (ORs) were calculated using conditional logistic regression. Results: Metformin was associated with a lower risk of developing BCC (OR, 0.71; 95% confidence interval [CI], 0.61-0.83), even at low doses. No increased risk of developing SCC was observed. SCCis risk was mildly elevated in the 501-1500 daily dose unit category (OR, 1.40; 95% CI, 1.00-1.96). Limitations: This study was retrospective in nature with the inability to adjust for ultraviolet exposure, Fitzpatrick skin type, and comorbidities. Conclusion: Metformin is associated with decreased risk of BCC development, even at low doses. Metformin might have potential as a chemoprotective agent for patients at high risk of BCC, although this will need confirmation in future studies. Keywords: basal cell carcinoma; keratinocyte carcinoma; metformin; squamous cell carcinoma; squamous cell carcinoma in situ.