Reduced risk of lung cancer with metformin therapy in diabetic patients: a systematic review and meta-analysis
- PMID: 24920786
- DOI: 10.1093/aje/kwu124
Reduced risk of lung cancer with metformin therapy in diabetic patients: a systematic review and meta-analysis
Abstract
Emerging evidence from epidemiologic studies and basic science suggests an inverse association between metformin use and cancer risk in diabetic patients. However, the association with lung cancer is not consistent. We summarized the evidence currently available (2009-2013) and explored sources of heterogeneity. Metformin therapy was associated with significantly lower risks of cancers of the lung (4 studies; pooled relative risk = 0.71, 95% confidence interval (CI): 0.55, 0.95; P = 0.02) and respiratory system (6 studies; pooled relative risk = 0.85, 95% CI: 0.75, 0.96; P = 0.01). There was evidence of moderate heterogeneity (I(2) > 50%). The major sources of heterogeneity were smoking adjustment status and cancer site. The relative risk from studies that adjusted for smoking was 1.16-fold (95% CI: 1.00, 1.35) closer to the null than that from studies not adjusting for smoking. The relative risk of respiratory cancer was 1.23-fold (95% CI: 1.02, 1.49) closer to the null than that for lung cancer. In conclusion, metformin use appears to be associated with lower risks of lung and respiratory cancer in diabetic patients. However, caution regarding overestimation is needed, since adjustment for smoking attenuates the association.
Keywords: chemoprevention; diabetes; lung cancer; metformin; smoking.
© The Author 2014. Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.
Comment in
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One author replies.Am J Epidemiol. 2014 Dec 15;180(12):1217-8. doi: 10.1093/aje/kwu314. Epub 2014 Nov 12. Am J Epidemiol. 2014. PMID: 25395023 No abstract available.
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Re.: "Reduced risk of lung cancer with metformin therapy in diabetic patients: a systematic review and meta-analysis".Am J Epidemiol. 2014 Dec 15;180(12):1216-7. doi: 10.1093/aje/kwu311. Epub 2014 Nov 12. Am J Epidemiol. 2014. PMID: 25395024 No abstract available.
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Re: "reduced risk of lung cancer with metformin therapy in diabetic patients: a systematic review and meta-analysis".Am J Epidemiol. 2014 Dec 1;180(11):1130-1. doi: 10.1093/aje/kwu296. Epub 2014 Nov 4. Am J Epidemiol. 2014. PMID: 25414205 No abstract available.
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One author replies.Am J Epidemiol. 2014 Dec 1;180(11):1131-2. doi: 10.1093/aje/kwu297. Epub 2014 Nov 4. Am J Epidemiol. 2014. PMID: 25414206 No abstract available.
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