Is metabolic syndrome associated with high tumor grade and stage of bladder cancer: a systematic review and meta-analysis

BACKGROUND: The aim of our study was to elaborate the association between metabolic syndrome (MS) and the tumor stage and grade of bladder cancer (BC). METHODS: A systematic review and pooled analysis on PubMed, the Cochrane Library, Embase, Web of Science, CNKI, WANFANG and VIP from databases inception to July 24, 2020 was conducted by two independent authors. Relative risk (RR) was used as pooled effect estimates. The data analysis was accomplished by STATA 14.2. RESULTS: Three English and four Chinese articles were included in the final analysis. A pooled analysis of six studies showed that patients in MS group were at a 1.94-fold risk of high-stage BC when compared to their counterparts (RR: 1.94; 95% CI: 1.59–2.37), and the difference was statistically significant. For the components of MS, except for hypertension, patients with obesity (RR: 1.61; 95% CI: 1.33–1.95), hyperglycemia (RR: 2.20; 95% CI: 1.49–3.26) and low high-density lipoprotein cholesterol (HDL) (RR: 1.98; 95% CI: 1.51–2.58) had significantly higher risks of high-stage BC than the control groups. A pooled analysis of six studies indicated that MS can contribute substantially to the vulnerability of high-grade BC with significant difference (RR: 1.50; 95% CI: 1.37–1.65). Furthermore, patients with obesity (RR: 1.41; 95% CI: 1.18–1.69), hyperglycemia (RR: 1.42; 95% CI: 1.30–1.56), hypertension (RR: 1.13; 95% CI: 1.03–1.24), low HDL (RR: 1.29; 95% CI: 1.14–1.46) and high triglyceride (TG) (RR: 1.28; 95% CI: 1.11–1.46) were at a higher risk of high-grade BC than their counterparts. CONCLUSIONS: This meta-analysis revealed that MS and its components might be associated with high BC stage and grade.