THE RISK OF PANCREATIC-CANCER FOLLOWING PANCREATITIS - AN ASSOCIATIONDUE TO CONFOUNDING

Background & Aims: Chronic pancreatitis has been suggested as a causal risk factor for pancreatic cancer in a recent study, The aim of this study was to clarify the relationship between chronic pancreatitis and pancreatic cancer, Methods: All patients in the Swedish Inpatient Reg ister with a discharge diagnosis of pancreatitis from 1965 to 1983 wer e identified, They were stratified into subcohorts as follows: (1) one episode of unspecified pancreatitis (n = 823); (2) one episode of acu te pancreatitis (n = 24,753); (3) recurrent pancreatitis (n = 7328); a nd (4) chronic pancreatitis (n = 4546), We also identified those with associated diagnoses indicating gallbladder disease or alcoholism, The patients were followed up through record linkage to the nationwide Sw edish Cancer Register, Death Register, and Migration Register, Results : After exclusion of cancers occurring in the first year, there were e xcess risks for pancreatic cancer in all subcohorts, However, the risk s declined with time in all subcohorts, A persistent excess risk after 10 years was restricted to patients with associated alcohol abuse (st andardized incidence ratio, 3.8; 95% confidence interval, 1.5-7.9). Co nclusions: The findings are not consistent with reports that pancreati tis is causally associated with a long-term risk of pancreatic cancer, Selection bias, alcohol consumption, and smoking may contribute to so me of the patterns of risk that have been observed.