Identification of prognostic factors in patients with metastatic gastrointestinal stromal tumors

Abstract

Purpose: Gastrointestinal stromal tumors (GISTs) have a complex biology which is reflected by a marked clinical heterogeneity. Thus, there has been great interest in identifying prognostic factors influencing tumor recurrence and survival. The aim of this study was to identify potential clinical and immunohistochemical prognostic factors that may affect survival and treatment outcomes inpatients with metastatic GISTs. Methods: Between 2000 and September 2011, a total of 41 patients with metastatic GISTs (29 males and 12 females; mean age: 57.4 +/- 11.8 years; range 29-74) were referred to the Department of Oncology, Uludag University Medical School. Survival analysis for a number of potential prognostic factors was made with the main outcome results of progression-free survival (PFS) and overall survival (OS). Results: The most common sites of isolated metastases comprised the liver (n=18), followed by lymph nodes (n=5), the omentum (n=1), and the mesothelium (n=1). The remaining patients had metastases at multiple sites. Cox regression analysis identified ileal location as the only significant predictor of poor PFS both after first-line (p=0.023) and second-line therapy (p=0.016). Tumor location in the ileum (p=0.025) and S100 immunoreactivity (p=0.041) were both independent predictors of OS. Conclusion: Tumor site and S100 positivity were the main significant independent predictors of clinical outcomes in patients with metastatic GISTs treated by standard of care.