Gastrointestinal Stromal Tumors: A Clinicopathological and Immunohistochemical Study of 65 Cases

Objective: The clinical behavior of gastrointestinal stromal tumors is divergent. The aim of the present study was to define the clinicopathological features that determine the patient's outcome. Material and Method: Sixty-five gastrointestinal stromal tumors were reviewed with their histological, immunohistochemical and clinical features and compared with their clinical outcome statistically. Results: Tumors were located in the stomach (n=39, 60%), small intestine (n=22, 33.8%) and large intestine (n=4, 6.2%). Immunohistochemically, CD 117 positivity was found in 90.8%, whereas CD34, Smooth muscle actin, Desmin and S100 positivity was found in 73.3%, 61.7%, 11.7% and 28.3% of tumors respectively. All six "CD 117-negative" cases expressed DOG-1. The mean Ki-67 proliferation index was 8.69%±12.76. Liver metastasis was detected in seven cases. A significant association was detected between decreased mean survival time and increased tumor size (p<0.001), large bowel localization (p=0.047), mitosis (p<0.001), the presence of necrosis (p=0.001), metastasis (p=0.033), Ki-67 proliferation index (p=0.002) and risk category (p