The present study investigated the relationship between metabolic phenotypes and the risk of cancer in a Japanese population using the criteria of metabolic phenotypes based on an examination and those based on questionnaires. We used data from 25,357 subjects for examination-based analyses and those from 53,042 subjects for questionnaire-based analyses in the Japan Multi-Institutional Collaborative Cohort Study. Metabolic phenotypes were defined by classifying subjects according to their BMI (obesity: BMI ≥25 kg/m2; normal weight: BMI <25 kg/m2) and the number of metabolic abnormalities. Metabolic abnormalities were defined according to metabolic syndrome components of the Joint Interim Statement Criteria for examination-based analyses and self-reported histories of diabetes, dyslipidemia, and hypertension for questionnaire-based analyses. Cox proportional hazards regression analyses adjusted for potential confounders were performed for total and site-specific cancer incidence according to metabolic phenotypes. Metabolically unhealthy obesity (MUHO) was significantly associated with cancer incidence in both examination-based [HR (95% CI): 1.17 (1.01-1.36)] and questionnaire-based analyses [HR (95% CI): 1.15 (1.04-1.26)]. Regarding site-specific cancer in questionnaire-based analyses, metabolically healthy obesity and MUHO were associated with colorectum and liver cancers in all subjects and with breast cancer in female subjects. Subjects with a metabolically unhealthy normal weight had a higher risk of pancreatic cancer. Moreover, MUHO was associated with corpus uteri cancer in female subjects. This prospective cohort study suggests that metabolic phenotypes are important risk factors for total and some site-specific cancers in Japanese adults.
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