Allergic Diseases and Risk of Malignancy of Gastrointestinal Cancers.

The aim of this study was to investigate the effect of allergic diseases, including allergic rhinitis, asthma, and atopic dermatitis, on the development of gastrointestinal (GI) cancers. We analyzed 9,892,633 Korean adults who underwent a medical check-up in the year 2009, and they were followed up until the year 2017. Allergic diseases and cancers were defined using the International Classification of Disease Codes. A Cox proportional hazards model was adapted to calculate the hazard ratios (HRs) and 95% confidence intervals (CIs). During a 7.3-year follow-up period, 48,045 patients were diagnosed with cancer. For all-combined allergic diseases, significant inverse associations were observed for cancers of the esophagus, stomach, colorectum, and liver (adjusted hazard ratios (aHRs [95% confidence interval, CI] 0.86 [0.82-0.91], 0.93 [0.91-0.94], 0.95 [0.93-0.96], and 0.90 [0.88-0.92], respectively). The sex-stratified analysis showed that the preventive effect of allergic diseases was persistent in gastric, colorectal, and liver cancers regardless of sex, while the inverse associations with esophageal and pancreatic cancers were observed only in men (aHR [95% CI] 0.84 [0.80-0.89] and 0.96 [0.93-0.99]). Allergic diseases, particularly allergic rhinitis, in adults were significantly associated with a decreased risk of most GI cancers, except for gallbladder and biliary tract cancers.