Associations between obesity, metabolic syndrome, and endometrial cancer risk in East Asian women

OBJECTIVE: This study investigated the associations between obesity, metabolic syndrome (MetS), the combination of these two components as a metabolic obesity phenotype, and endometrial cancer risk in East Asian women. METHODS: A total of 6,097,686 cancer-free women aged 40–74 years who underwent the National Health Insurance Service health examination between 2009 and 2010 were included. Cancer incidence was identified using the healthcare utilization database. Associations between baseline obesity (body mass index <23 kg/m(2), 23–24.9 kg/m(2), ≥25 kg/m(2)), MetS, each component of MetS, MetS stratified by obesity status, combination of obesity and MetS, and endometrial cancer risk were investigated using hazard ratios (HRs). RESULTS: Obesity, each component of MetS, and MetS increased the endometrial cancer risk. After these factors were mutually adjusted for, the association did not change. When stratified by obesity, MetS and MetS components were not associated with endometrial cancer in normal-weight or overweight women. However, in obese women, MetS and MetS components increased the risk of endometrial cancer (HR=1.29; 95% confidence interval [CI]=1.20–1.39). Compared with normal-weight women without MetS, endometrial cancer risk was not increased in normal-weight women with MetS. Overweight women showed an increased risk of endometrial cancer irrespective of the presence of MetS (HR=1.37 and 1.38, respectively). The HR of obese women with MetS was higher than that of obese women without MetS (HR=2.18 and 1.75). CONCLUSION: The association between MetS and endometrial cancer was most prominent in obese women, suggesting that obese women with MetS would be more vulnerable to endometrial cancer.