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

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.We evaluated the risk of developing PDAC two or more years after a new diagnosis of CP.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.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.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.