Analysis of Prognostic and Immunohistochemical Factors in Gastrointestinal Stromal Tumors with Malignant Potential

The aim of this study was to analyze 37 patients with malignant primary gastrointestinal stromal tumors and to compare the findings and their therapeutic implications with those previously reported. The medical records of 37 patients who were diagnosed and operated on between January 1996 and December 2002 were retrospectively reviewed. The patients' age, tumor size, type of surgery, histologic type, mitotic counts, presence of necrosis, Ki-67 proliferative index, National Institutes of Health 2001 consensus classification, immunohistochemical staining, and recurrence were examined to analyze factors affecting survival. Overall actuarial survival for all patients was 46%. When analyzed by type of resection, the complete resection group (R0 resection) had a mean overall survival of 48.2 +/- 6.18 months compared with the patients with incomplete resection (R1-R2) who survived a mean of 10.8 +/- 3.2 months (P=0.00). Univariate analysis showed development of recurrence (P=0.00), tumor size of 8 cm or greater (P=0.05), Ki-67 proliferative index greater than 0.82 (P=0.0448), desmin staining (P=0.0076), age younger than 49 years (P=0.0009), and incomplete resection (P=0.00) to be significantly correlated with a poor survival. In multivariate analysis, desmin staining (P=0.031), tumor size (P=0.033), age (P=0.01), recurrence (P=0.038), and R0 resection (P=0.02) were significant independent prognostic factors. We recommend that more careful preoperative and more frequent postoperative follow-up examinations be performed for patients with large tumors, age of younger than 49 years, and Ki-67 proliferative index greater than 0.82.