Pancreatitis and the risk of pancreatic cancer. International Pancreatitis Study Group.

The results of case-control studies and anecdotal reports suggest that pancreatitis may be a risk factor for pancreatic cancer, but there have been no studies of sufficient size and power to assess the magnitude of the relation between these two diseases. We undertook a multicenter historical cohort study of 2015 subjects with chronic pancreatitis who were recruited from clinical centers in six countries. A total of 56 cancers were identified among these patients during a mean (+/-SD) follow-up of 7.4 +/- 6.2 years. The expected number of cases of cancer calculated from country-specific incidence data and adjusted for age and sex was 2.13, yielding a standardized incidence ratio (the ratio of observed to expected cases) of 26.3 (95 percent confidence interval, 19.9 to 34.2). For subjects with a minimum of two or five years of follow-up, the respective standardized incidence ratios were 16.5 (95 percent confidence interval, 11.1 to 23.7) and 14.4 (95 percent confidence interval, 8.5 to 22.8). The cumulative risk of pancreatic cancer in subjects who were followed for at least 2 years increased steadily, and 10 and 20 years after the diagnosis of pancreatitis, it was 1.8 percent (95 percent confidence interval, 1.0 to 2.6 percent) and 4.0 percent (95 percent confidence interval, 2.0 to 5.9 percent), respectively. The risk of pancreatic cancer is significantly elevated in subjects with chronic pancreatitis and appears to be independent of sex, country, and type of pancreatitis.