Onset of pancreatic cancer before and after acute pancreatitis: A multicenter longitudinal cohort study.

Background: Pancreatic cancer (PC) is a leading cause of cancer mortality, often diagnosed at advanced stages. Acute pancreatitis (AP), particularly idiopathic cases, may serve as an early indicator of PC.

Objective: This multicenter cohort study investigated the incidence of PC before and after an AP episode, focusing on idiopathic AP and the role of pseudocysts as potential early markers for PC development.

Methods: We analyzed data from 2356 AP patients across 25 centers, with a median follow-up of 4.1 years (IQR: 1.6-6.8 years). Patients were categorized into 'PC before AP' and 'PC after AP' groups, and relative risk (RR) and adjusted odds ratios (OR) were calculated for idiopathic AP cases to quantify PC risk.

Results: Among all cases, 69 patients (2.9 %) developed PC: 1.4 % (n = 34) before and 1.5 % (n = 35) after AP. Idiopathic AP cases had a fourfold higher risk of PC (OR = 4.46, [2.25-8.85]). Notably, pseudocysts were five times more prevalent in the PC group (14 %) compared to controls (3 %) (RR = 5.66; p < 0.01), often located at the tumor site. PC developed in 3 % of idiopathic AP cases versus 1.0 % in non-idiopathic cases. The median time to PC diagnosis post-AP was 373 days.

Conclusion: Idiopathic AP and pseudocyst formation significantly elevate the risk of PC, particularly within two years. These findings underscore the need for structured follow-up and early screening in idiopathic AP cases to improve PC detection and survival outcomes.