Increased risk of colorectal cancer among patients with biliary tract inflammation: a 5-year follow-up study.

The purpose of the study was to investigate the risk of colorectal cancer among patients with biliary tract inflammation (BTI) compared to non-BTI patients during a 5-year follow-up period. The study group comprised 1,613 patients with BTI, among which 32 cases (1.98%) developed colorectal cancer. The comparison group included 8,065 randomly selected subjects (5 for every patient with BTI), 74 of whom contracted colorectal cancer (0.92%). Stratified Cox proportional hazard regressions were calculated to estimate the adjusted hazard of colorectal cancer between the study group and comparison group. The adjusted hazard ratio for colorectal cancer for patients with BTI was 6.54 times (95% CI = 3.07-13.92) as high as for those without BTI within a 1-year follow-up period, 3.20 times (95% CI = 1.93-5.30) as high within a 3-year follow-up period, and 2.21 times (95% CI = 1.45-3.37) as high within a 5-year follow-up period. We also found that the adjusted hazard ratio for colorectal cancer for those with bile duct inflammation was 3.30 times (95% CI = 1.87-5.84) as high as for those without BTI within the 5-year follow-up period. However, no increased hazard of colorectal cancer was observed for patients with gallbladder inflammation. We concluded that patients with BTI had a significantly higher risk of colorectal cancer compared to patients without BTI.