The association between metabolic syndrome and cancer: A systematic review

Background: Metabolic syndrome (MetS), a cluster of central adiposity, hypertension, dysglycemia, hypertriglyceridemia, and low HDL cholesterol, has been identified as a possible determinant of lung cancer incidence and mortality. Objective: To evaluate the association between MetS and lung cancer incidence and mortality, and examine sources of heterogeneity across studies. Methods: A systematic review was conducted in accordance with PRISMA 2020 guidelines. CINAHL, Web of Science, and PubMed were searched from January 2000 through March 2025 for studies in adults that reported adjusted effect estimates for the relationship between MetS, defined by NCEP ATP III, IDF, or similar criteria, and cancer outcomes. Two reviewers independently screened studies, extracted data, and assessed risk of bias using the Newcastle-Ottawa Scale. Narrative synthesis and random effects meta-analysis were performed, with subgroup analyses by sex, smoking status, geographic region, and MetS definition. Heterogeneity was evaluated with the I² statistic and Cochran's Q, and publication bias was examined using Egger's test. Results: Of 2,607 records screened, 11 studies met the inclusion criteria. In the meta-analysis of lung cancer incidence, the pooled hazard ratio was 1.18 (95% CI 1.04-1.33, p =.010), indicating a higher hazard of lung cancer among individuals with MetS. Heterogeneity was substantial (I² = 97.6 percent, p < .001). Conclusions: The reviewed studies indicate that MetS has an association with increased lung cancer incidence. Clinical evaluation for MetS may identify individuals at elevated cancer risk, supporting early lung cancer screening and preventive strategies. Further research should determine whether integrating cancer prevention into MetS management influences long-term cancer outcomes.