The impact of metformin use on survival in prostate cancer: a systematic review and meta-analysis

Yao Xiao, Lei Zheng, Zubing Mei, Changbao Xu, Changwei Liu, Xiaohan Chu and Bin Hao _

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Oncotarget. 2017; 8:100449-100458. https://doi.org/10.18632/oncotarget.22117

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Yao Xiao1,*, Lei Zheng2,*, Zubing Mei3, Changbao Xu1, Changwei Liu1, Xiaohan Chu1 and Bin Hao1

1Department of Urology, The Second Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan Province, China

2Department of Endocrinology, The First Affiliated Hospital of Chinese PLA General Hospital, Beijing, China

3Department of Anorectal Surgery, Shuguang Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China

*These authors contributed equally to this work

Correspondence to:

Bin Hao, email: [email protected]

Zubing Mei, email: [email protected]

Keywords: prostate cancer; prognosis; metformin; meta-analysis; survival

Received: May 10, 2017     Accepted: October 13, 2017     Published: October 31, 2017


Background: Metformin has been implicated to reduce the risk of prostate cancer (PCa) beyond its glucose-lowering effect. However, the influence of metformin on prognosis of PCa is often controversial.

Results: A total of 13 cohort studies encompassing 177,490 individuals were included in the meta-analysis. Data on overall survival (OS) and cancer-specific survival (CSS) was extracted from 8 and six studies, respectively. Comparing metformin users with non-metformin users, the pooled hazard ratios (HRs) for OS and CSS were 0.79 (95% confidence interval [CI] 0.63–0.98) and 0.76 (95% CI 0.57–1.02), respectively. Subgroup analyses stratified by baseline charcteristics indicated significant CSS benefits were noted in studies conducted in USA/Canada with prospective, large sample size, multiple-centered study design. Five studies reported the PCa prognosis for recurrence-free survival (RFS) and metformin use was significantly associated with patient RFS (HR 0.74, 95% CI, 0.58–0.95).

Methods: Relevant studies were searched and identified using PubMed, Embase and Cochrane databases from inception through January 2017, which investigated associations between the use of metformin and PCa prognosis. Combined HRs with 95% CI were pooled using a random-effects model. The primary outcomes of interest were OS and CSS.

Conclusions: Our findings provide indication that metformin therapy has a trend to improve survival for patients with PCa. Further prospective, multi-centered, large sample size cohort studies are warranted to determine the true relationship.

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