Epidemiology of gastrointestinal stromal tumors in a defined Canadian Health Region: a population-based study.

The aim of this study was to determine the incidence and the clinical and pathological features of gastrointestinal stromal tumors within a nonselected, well-defined Canadian Health Region. A population-based cohort study of all adult patients diagnosed with gastrointestinal stromal tumors was conducted in the Calgary Health Region from April 2000 to March 2004. All charts and pathological specimens were reviewed for clinical, histological, and antigenic features. The age-adjusted and gender-adjusted annual incidence rate was 0.91/10(5) person-years. There was a trend for increased incidence with routine use of CD117. The only identified risk was advancing age (age >or=50; rate ratio = 4.6; P = .0006). All samples were positive for CD117. At presentation, 19% were at intermediate and 19% were at high risk of becoming malignant, with 14% being overtly metastatic. This is the first North American study to define the incidence and the clinical and pathologic features of gastrointestinal stromal tumors based on current diagnostic criteria.