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Impact of metformin on clinical outcomes among men with prostate cancer: a systematic review and meta-analysis

Raval AD, Thakker D, Vyas A, Salkini M, Madhavan S, Sambamoorthi U

Prostate cancer and prostatic diseases, 2015

Abstract

BACKGROUND: Conflicting evidence exists regarding the beneficial effects of metformin in prostate cancer. To determine the association between metformin and clinical outcomes in prostate cancer using systematic review and meta-analysis.

METHODS: Original articles published in English until third week of July, 2014 were searched in electronic databases (Medline-Ovid, Scopus, The Cochrane Library, Web of Science, ProQuest) for studies on metformin use in prostate cancer. The clinical outcomes assessed were: development of biochemical recurrence, metastases or castration-resistant metastatic cancer, all-cause and prostate cancer-specific mortality. Meta-analysis was performed to calculate the pooled hazard ratio (pHR) and their 95% confidence interval (95% CI). Heterogeneity between the studies was examined using I2 statistics. Sensitivity analysis was conducted to assess the robustness of findings and publication bias was assessed by the Egger's regression asymmetry test and contour plot.

RESULTS: Out of 230 retrieved citations, eight retrospective cohort studies and one nested-case-control study met the inclusion criteria. Metformin use was marginally associated with reduction in the risk of biochemical recurrence (pHR: 0.82, 95% CI: 0.67, 1.01, P-value=0.06, I2=25%, five studies). Metformin use was not significantly associated with metastases (pHR: 0.59, 95% 0.30-1.18, P-value=0.14, I2=74%, three studies), all-cause mortality (pHR: 0.86; 95% CI, 0.67, 1.10, P-value=0.23, I2:…

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