Background
Previous meta-analyses revealed that obesity confers a risk of gastric cancer. On the other hand, metabolically healthy obese (MHO) individuals, who are healthier than metabolically abnormal obese (MAO) individuals, have lower risks of colon cancer and breast cancer. However, the association between MHO and incident gastric cancer is unclear.
Methods
This historical cohort study included 19,685 Japanese individuals who participated in health-checkup programs from 2003 to 2016. Each subject was classified as metabolically healthy (MH) (no metabolic abnormalities) or metabolically abnormal (MA) (one or more metabolic abnormalities), according to four metabolic factors (hypertension, impaired fasting glucose, hypertriglyceridemia and low high density lipoprotein-cholesterol). Obese (O) or non-obese (NO) was classified by a body mass index cutoff of 25.0 kg/m2. Hazard ratios of metabolic phenotypes for incident gastric cancer were calculated by the Cox proportional hazard model with adjustments for age, sex, alcohol consumption, smoking and exercise.
Results
Over the median follow-up period of 5.5 years, 78 participants developed gastric cancer. Five-years cumulative incident rate of gastric cancer was 0.2% (case/n = 17/8,331) in MHNO, 0.2% (1/653) in MHO, 0.5% (35/7,276) in MANO and 0.7% (25/3,425) in MAO. Compared with MHNO, the adjusted hazard ratios for development of gastric cancer were 0.69 (95%CI 0.04–3.39, p = 0.723) in MHO, 1.16 (95%CI 0.63–2.12, p = 0.636) in MANO and 2.09 (95%CI 1.10–3.97, p = 0.024) in MAO.
Conclusions
This study shows that individuals with MAO, but not those with MHO, had an elevated risk for incident gastric cancer.