Increased Risk of Colorectal Cancer among Patients with Biliary Tract Inflammation: A Five-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 1613 patients with BTI,
among which 32 cases (1.98%) developed colorectal cancer. The comparison group
included 8065 randomly selected subjects (five 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 five-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.