Epidemiology of gastrointestinal stromal tumour (GIST) is sparsely described. We report a population-based consecutive case series of GIST over three decades from south-western Norway.
All mesenchymal tumours registered at Stavanger University Hospital between 1980 and 2009 were reviewed and those of the gastrointestinal tract were reclassified with regard to histomorphology and/or immunohistochemistry profiles consistent with GIST. Reported are patients' characteristics and GIST incidence and prevalence estimated using population statistics.
Fifty-two cases were identified; 62% of the patients were women. Median age at diagnosis was 67 years. Fifty-eight percent of the tumours were located in the stomach, 38% in the small bowel and one each in colon and rectum. One third were considered to be high risk according to the NIH consensus criteria. The crude incidence rate of GIST was 1.8 per million in the study population per year in the 5-year period 1980-1984, and increased to around 6 in the following years with a peak at 12.5 per million in 2000-2004. The over all crude incidence rate for 1980-2009 was 6.5 per million (95% CI 4.8-8.3 per mill.). Standardized age- and gender adjusted incidence for Norway was 7.4 per million (95% CI 5.4-9.4). The number of patients alive with GIST increased over the study period, with a peak in 2000-2004 at 92.1 per million (95% CI 60.7-134.0 per mill.). One in five had an additional gastrointestinal cancer, located in the colon (n=6), rectum (n=2), stomach (n=3) or, pancreas (n=1).
Incidence of GIST in the south-western part of Norway is relatively stable and towards the lower end of the range reported in the worldwide literature. An increasing prevalence likely reflects therapy effects. Synchronous gastrointestinal cancers are relatively common in patients with GIST.