Nilsson B et al. (2005) Gastrointestinal stromal tumors: the incidence, prevalence, clinical course, and prognostication in the preimatinib mesylate era—a population-based study in western Sweden. Cancer 103: 821–829

Results from a population-based study evaluating gastrointestinal stromal tumor (GIST) patients have led researchers to propose that risk scores based solely on tumor size and proliferative index could be more useful than current methods for assessing prognosis.

The study evaluated 288 primary GIST patients from a province in western Sweden, identified from the records of 1,460 potential cases diagnosed between 1983 and 2000. GIST tumors were detected due to patient symptoms (n = 196), incidentally during surgery (n = 60) or incidentally at the time of autopsy (n = 29). Between 1983 and 2000, only 28% of patients were originally diagnosed with GIST; this figure increased to 67% for patients diagnosed between 1995 and 2000. The study found that the annual incidence and prevalence of GIST were 14.5 per million and 129 per million, respectively.

Tumor size, degree of cellular pleomorphism, mitotic rate, and average and maximum Ki-67 proliferative index were found to be statistically significant with regard to decreased overall survival. Of these, only tumor size and maximum Ki-67 proliferative index were independent prognostic factors. Nilsson et al. conclude that a prognosis based solely on a risk score calculated by addition of these two factors divided the patients into two risk groups: those with a risk score >7 had a poor prognosis, and those with a risk score of ≤7 had an excellent prognosis.