Metabolically healthy overweight/obesity and cancer risk: A representative cohort study in Taiwan

Objective: Many cancers are caused by overweight; however, cancer risk varies among individuals with obesity. Few studies are addressing the relationship between metabolic obesity phenotypes and cancer. This study investigates the association between metabolically healthy overweight (MHOW) or metabolically healthy obesity (MHO) and cancer incidence. Methods: In a nationwide, representative community-based prospective cohort study, 5734 Taiwanese adults were classified into eight phenotypes according to body mass index (underweight <18.5; normal weight 18.5-23.9; overweight 24-26.9; and obese >= 27 kg/m(2)) and metabolic status (healthy/unhealthy). Participants with healthy cardiometabolic blood profiles included in the metabolic syndrome criteria and an absence of hypertension, diabetes, and hyperlipidemia were considered metabolically healthy. We used the Cox proportional hazards models to estimate the adjusted hazard ratio (HR) and 95% confidence intervals (95% CI). Results: During 73,389 person-years of follow-up, 428 incident cancers were identified. Compared to the participants with metabolically healthy normal weight, participants with MHOW (adjusted HR 1.39, 95% CI, 0.90-2.13) or MHO (adjusted HR 1.07, 95% CI, 0.51-2.22) had a tendency toward a higher risk of cancer. These associations were stronger in MHOW (adjusted HR 1.77, 95% CI, 1.09-2.86) or MHO (adjusted HR 1.39, 95% CI, 0.66-2.93) participants younger than 65 years. Conclusions: This study was the first to investigate the impact of metabolic obesity phenotype on the incidence of cancer in the Taiwanese population. Even in the absence of metabolic abnormalities, overweight, and obesity may cause a modest increase in the risk of developing cancer.