A widely prescribed type 2 diabetes medication may offer unexpected protection against the most common forms of skin cancer, according to new research published in the Journal of Drugs in Dermatology. The study reveals that patients taking metformin experienced substantially lower risks of developing both basal cell carcinoma (BCC) and squamous cell carcinoma (SCC).
Significant Risk Reduction Across Cancer Types
The comprehensive analysis, based on National Institutes of Health data, examined over 8,000 individuals with BCC and more than 4,100 with SCC, comparing them against matched control groups. The findings were striking: without adjusting for other factors, metformin users showed 54% lower odds of developing BCC and 35% lower odds of SCC.
When researchers adjusted for medications known to increase skin cancer risk - including hydrochlorothiazide, photosensitizing medications, TNF inhibitors, and statins - the protective effect became even more pronounced. Adjusted results showed 67% lower odds of BCC and 55% lower odds of SCC among metformin users.
Racial Variations in Protection
The study revealed important variations in metformin's protective effects across different racial groups. Notably, Black patients showed a different pattern for SCC prevention, with only 39% lower unadjusted odds compared to non-users. However, this figure improved to 78% in multivariable analysis.
"This discrepancy could stem from the fact that SCC in these patients often develops in sunprotected areas and is strongly linked to chronic scarring and inflammation, factors that may not be influenced by metformin use," the study authors explained.
Clinical Implications and Future Research
The findings carry significant implications for public health, particularly given that approximately 5.4 million cases of non-melanoma skin cancer are diagnosed annually in the United States. The research suggests potential new preventive strategies for high-risk populations.
However, the study authors acknowledged several limitations. The analysis relied on electronic health records for prescription data, which may underestimate actual metformin use. Additionally, the study categorized metformin use simply as "ever use" versus "never use," leaving questions about optimal dosage and duration unanswered.
The researchers emphasized the need for further investigation into metformin's potential as a chemopreventive agent, particularly in patients of color. "While previous population-level studies have yielded mixed results, the nuanced variations among racial groups found in our study underscore the need for personalized approaches in evaluating metformin's anti-cancer properties," they concluded.
