Incidence and Risk of Pancreatic Cancer in Patients with a New Diagnosis of Chronic Pancreatitis

Background: Chronic pancreatitis (CP) is a risk factor for pancreatic ductal adenocarcinoma (PDAC); nevertheless, the true incidence of PDAC in CP patients in the United States remains unclear. Aims: We evaluated the risk of developing PDAC two or more years after a new diagnosis of CP. Methods: Retrospective study of veterans from September 1999 to October 2015. A three-year washout period was applied to exclude patients with preexisting CP and PDAC. PDAC risk was evaluated in patients with new-diagnosis CP and compared with controls without CP using Cox-proportional hazards model. CP, PDAC, and other covariates were extracted using ICD-9 codes. Results: After exclusions, we identified 7,883,893 patients [new-diagnosis CP − 21,765 (0.28%)]. PDAC was diagnosed in 226 (1.04%) patients in the CP group and 15,858 (0.20%) patients in the control group (p < 0.001). CP patients had a significantly higher PDAC risk compared to controls > 2 years [adjusted hazard ratio (HR) 4.28, 95% confidence interval (CI) 3.74–4.89, p < 0.001], 5 years (adjusted HR 3.32, 95% CI 2.75–4.00, p < 0.001) and 10 years of follow-up (adjusted HR 3.14, 95% CI 1.99–4.93, p < 0.001), respectively. By multivariable analysis, age (odds ratio 1.02, 95% CI 1.00–1.03, p = 0.03), current smoker (odds ratio 1.67, 95% CI 1.02–2.74, p = 0.042), current smoker + alcoholic (odds ratio 2.29, 95% CI 1.41–3.52, p < 0.001), and diabetes (odds ratio 1.51, 95% CI 1.14–1.99, p = 0.004) were the independent risk factors for PDAC. Conclusion: Our data show that after controlling for etiology of CP and other cofactors, the risk of PDAC increased in CP patients after two years of follow-up, and risk was consistent and sustained beyond 5 years and 10 years of follow-up.