BackgroundSeveral studies have explored the prognostic value of sirtuin 3 (SIRT3) in various cancers, but obtained inconsistent results. The current systematic review and meta-analysis was conducted to investigate the association between SIRT3 expression and prognosis in various cancers.MethodsPubMed, Embase, Web of Science and the Cochrane Library were comprehensively retrieved by the end of September 29, 2017. All the relevant studies were checked and included in the meta-analysis if they met the inclusion criteria.ResultsA total of 17 studies involving 2,865 patients were included in the systematic review and meta-analysis. The results indicated that SIRT3 expression was not significantly associated with overall survival (OS) (hazard ratio [HR]=0.87, 95% CI=0.59–1.29, P=0.50) and disease-free survival (HR=0.87, 95% CI=0.57–1.31, P=0.50) in total various cancers. However, significant relationship between SIRT3 expression and OS in specific cancers was detected, including chronic lymphocytic leukemia (CLL) (HR=0.48, 95% CI=0.26–0.89, P=0.019), hepatocellular carcinoma (HCC) (HR=0.56, 95% CI=0.42–0.74, P<0.001), pancreatic carcinoma (PC) (HR=0.55, 95% CI=0.30–1.00, P=0.049), renal cell carcinoma (RCC) (HR=0.13, 95% CI=0.02–0.98, P=0.048), breast cancer (BC) (HR=2.53, 95% CI=1.83–3.67, P<0.001), colon cancer (CC) (HR=1.87, 95% CI=1.12–3.26, P=0.022) and non-small-cell lung cancer (NSCLC) (HR=2.20, 95% CI=1.38–3.50, P=0.001). Moreover, SIRT3 expression was obviously associated with tumor size (odds ratio [OR]=1.41, 95% CI=1.02–1.94, P=0.04), tumor differentiation (OR=1.52, 95% CI=1.08–2.16, P=0.02) and clinical stage (OR=2.07, 95% CI=1.23–3.46, P=0.01) in HCC.ConclusionSIRT3 was distinctly related to the OS in specific cancers. SIRT3 was an unfavorable prognostic factor in BC, CC and NSCLC; however, it was also a favorable prognostic factor in CLL, HCC, PC and RCC, especially in HCC.