Panacreatic cancer risk after benign gallbladder disease: A Swedish population-based cohort study

The purpose of this nationwide registry-based cohort study was to outline pancreatic cancer risk after benign gallbladder disease (GBD). Anatomically adjacent cancers were investigated to address incidental findings. We included all Swedes aged 20-79 years with histologically confirmed GBD (cholecystitis and/or cholecystectomy) in 1992-2016 and five matched non-exposed population comparators. Follow-up started one month after GBD and incidence rates (IR) and hazard ratios (HR) with 95 % confidence intervals (CI) up to 15 years after GBD were estimated using Poisson and Cox regression, respectively. Fully adjusted models included sex, age, year, education, type 2 diabetes, obesity, smoking-, and alcohol-related disorders. Analyses were stratified by follow-up and flexible parametric models applied to assess time-varying effects. Interaction models were used to identify patient groups at risk. 680 and 1890 incident pancreatic cancers were detected over 15 years in 130907 GBD exposed and 571618 non-exposed, respectively. An excess pancreatic cancer risk was mainly seen within the first 2 years; IR: 84 [95 % CI 73,95] versus 31 [95 % CI 27,34] per 100000 person-years corresponding to an HR of 2.74 [95 % CI 2.31,3.25]. The same pattern was noted for duodenal cancer while primary liver cancer risk was elevated across follow-up. An initial extrahepatic biliary cancer risk elevation shifted to a reduction over time. The 2-year pancreatic cancer risk was augmented in younger (age 20-49) individuals, HR 7.64 [95 % CI 3.73,15.65]. Our findings urge more studies on the clinical follow-up the first years after cholecystitis to detect early pancreatic cancer.