The metabolic syndrome and its components as prognostic factors in colorectal cancer: A meta‐analysis and systematic review

BACKGROUND AND AIM: Metabolic syndrome (MetS) increases the risk of colorectal cancer (CRC), and the impact of MetS on CRC prognosis remains controversial after the diagnosis of CRC has been established. This study aimed to explore the impact of the individual components and synergies of MetS on the prognosis of patients with CRC. METHODS: We searched articles published before August 3, 2022, in four databases, including PubMed, Embase, Cochrane Library, and ScienceDirect. The random‐effects model inverse variance method was used to estimate the summarized effect size. RESULTS: Patients with CRC with MetS were 1.342 times more likely to experience all‐cause mortality than those without MetS, and the 95% confidence interval (CI) of hazard ratio (HR) was 1.107–1.627 (P = 0.003). CRC‐specific mortality in patients with CRC with MetS was 2.122 times higher than in those without MetS, and the 95% CI of HR was 1.080–4.173 (P = 0.029). CRC‐specific mortality exhibited an increasing trend of risk with increased metabolic risk factors. The HR of CRC‐specific mortality for one, two, and three metabolic risk factors was 1.206 (95% CI, 1.034–1.407; P = 0.017), 1.881 (95% CI, 1.253–2.824; P = 0.002), and 2.327 (95% CI, 1.262–4.291; P = 0.007), respectively. CONCLUSIONS: Metabolic syndrome increased all‐cause and CRC‐specific mortality in patients with CRC. As a single component of MetS, diabetes mellitus increased overall mortality in patients with CRC, while obesity increased CRC‐specific mortality in patients with CRC, with a significant difference from non‐MetS. Moreover, the risk of CRC‐specific mortality increased with increasing number of metabolic risk factors.