Exploring the association between acute pancreatitis and biliary tract cancer: A large-scale population-based matched cohort study.

BACKGROUND

Biliary tract cancer (BTC) often goes undetected until its advanced stages, resulting in a poor prognosis. Given the anatomical closeness of the gallbladder and bile ducts to the pancreas, the inflammatory processes triggered by acute pancreatitis might increase the risk of BTC.

OBJECTIVE

To assess the association between acute pancreatitis and the risk of BTC.

METHODS

Using the Swedish Pancreatitis Cohort (SwePan), we compared the BTC risk in patients with a first-time episode of acute pancreatitis during 1990-2018 to a 1:10 matched pancreatitis-free control group. Multivariable Cox regression models, stratified by follow-up duration, were used to calculate hazard ratios (HRs), adjusting for socioeconomic factors, alcohol use, and comorbidities.

RESULTS

BTC developed in 0.94% of 85,027 acute pancreatitis patients and in 0.23% of 814,993 controls. The BTC risk notably increased within 3 months of hospital discharge (HR 82.63; 95% CI: 63.07-108.26) and remained elevated beyond 10 years of follow-up (HR 1.82; 95% CI: 1.35-2.47). However, the long-term risk of BTC subtypes did not increase with anatomical proximity to the pancreas, with a null association for gallbladder and extrahepatic tumors. Importantly, patients with acute pancreatitis had a higher occurrence of early-stage BTC within 2 years of hospital discharge than controls (13.0 vs. 3.6%; p-value <0.01).

CONCLUSION

Our nationwide study found an elevated BTC risk in acute pancreatitis patients; however, the risk estimates for BTC subtypes were inconsistent, thereby questioning the causality of the association. Importantly, the amplified detection of early-stage BTC within 2 years after a diagnosis of acute pancreatitis underscores the necessity for proactive BTC surveillance in these patients.