Body mass index and gastrointestinal cancer mortality in Korean adults: A prospective cohort study

Background: The association between body mass index (BMI) and mortality from gastrointestinal (GI) cancer remains unclear, especially in Asian populations.

Methods: A total of 510 148 Korean adults who participated in routine health examinations during the period 2002-2003 were followed up until 2013.

Results: During a mean follow up of 10.5 years, 7831 individuals died of GI cancer. Various associations with BMI were found: U-curve (overall GI, colorectal, liver, and gallbladder cancer), L-curve (stomach cancer), linear (esophageal, extrahepatic bile duct [EBD], and small intestine cancer), and none (pancreatic cancer). Overall GI cancer mortality was lowest at approximately 23.5-26 kg/m² . For cancers with linear associations, the multivariable adjusted hazard ratios per each 5 kg/m² higher BMI were 0.53 (95% confidence interval = 0.43-0.65, esophagus), 1.19 (1.02-1.40, EBD), and 0.64 (0.41-0.999, small intestine). For cancers with U-curve or L-curve associations, the corresponding hazard ratios ≥25 kg/m² were 1.19 (1.08-1.32, overall GI), 1.30 (1.04-1.64, colorectal), 1.28 (1.07-1.53, liver), and 1.30 (0.85-1.97, gallbladder), while in the range of <25 kg/m² , they were 0.81 (0.76-0.87, overall GI), 0.43 (0.32-0.58, esophagus), 0.70 (0.62-0.79, stomach), and 0.77 (0.65-0.90, colorectal), and these inverse associations did not weaken after excluding the first 7 years of follow up and ever smokers.

Conclusions: Both low and high BMIs were associated with excess mortality from GI cancers in Korean adults. EBD cancer had a positive association, while esophageal and small intestine cancers had inverse associations. Above 25 kg/m² , liver and colorectal cancers had positive associations with BMI, whereas below 25 kg/m² , stomach and colorectal cancers had inverse associations.