Comparative analysis of four histopathological classification systems to discriminate benign and malignant behaviour in gastrointestinal stromal tumors.

UNLABELLED The prognostic value of the four most common histopathological classification systems in gastrointestinal stromal tumors (GISTs) was evaluated retrospectively. PATIENTS AND METHODS Twenty-five consecutive patients with resected GIST and a follow-up of five years or more for surviving patients were included in this analysis. All the tumors were c-KIT (CD117) positive and were additionally re-evaluated for the number of mitoses per 50 high-power fields (HPF) and Ki-67 proliferation index. The four most commonly applied histopathological classification systems of the WHO, Franquemont (modified by using the Ki-67 proliferation index), Fletcher and Miettinen were applied to each patient. RESULTS The survival of patient groups classified by Franquemont (p = 0.03) and the WHO (p = 0.031) were of prognostic relevance, while the grouping of patients by classifications according to both, Fletcher and Miettinen did not show a significant prognostic value. CONCLUSION The classification systems of Franquemont (modified) or WHO appear to be advantageous for the evaluation of malignant potential and clinical outcome in patients with GISTs. Our data are merely hypothesis generating and should be validated in larger clinical studies.