The clinical relevance of the increasing incidence of intraductal papillary mucinous neoplasm

Background & aims: The incidence of intraductal papillary mucinous neoplasm (IPMN) is believed to be increasing; we investigated whether this is the result of increasing burden of disease or more diagnostic scrutiny.

Methods: In a retrospective cohort study, we calculated a trend in reported incidence of IPMN using data collected from Olmsted County, Minnesota, from 1985 to 2005. Total IPMN cases from the Olmsted database were identified through a keyword and International Classification of Diseases, 9th revision, search using a database from the Rochester Epidemiology Project, with all cases verified by subsequent chart review. The subsequent rate of IPMN-related carcinoma was calculated using data from the national Surveillance Epidemiology and End Results-9 database, reflecting trends from 1982 to 2007. Cases of IPMN-related carcinoma were identified in the Surveillance Epidemiology and End Results-9 database by limiting the search to histology codes for noninvasive and invasive IPMN.

Results: Between 1985 and 2005, there was a 14-fold increase in the age- and sex-adjusted incidence of IPMN, from 0.31 to 4.35 per 100,000 persons. From 2000 to 2001, the rate of reported carcinoma increased from 0.008 to 0.032 per 100,000 persons, but stabilized afterward, with a rate of 0.06 per 100,000 persons in 2007. Mortality from all causes of pancreatic cancer was stable between 1975 and 2007 (approximately 11 deaths per 100,000 individuals).

Conclusions: The incidence of IPMN has increased in the absence of an increase in IPMN-related or overall pancreatic cancer-related mortality, so it likely results from an increase in diagnostic scrutiny, rather than greater numbers of patients with clinically relevant disease.