Gastrointestinal stromal tumors (GISTs): clinical aspects

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors in the gastrointestinal tract. One of their features is the expression of the c-KIT/CD117 receptor. We will focus on describing the symptoms, clinical studies prior to diagnosis, histologic and immunohistochemical characteristics, as well as the progression of disease in a group of patients. Seventeen cases were diagnosed between December 1999 and April 2005. Mean age of patients was 64.5 (+/-11.9); 47% were women. Tumor location was as follows: 52.9% in the jejunum or ileum, 29.4% were gastric, 11.7% were in the duodenum, and 5.8% were located in the mesentery. Tumor size was 6.0 cm on average (+/-5.0); 47% were asymptomatic, and to a lesser degree caused abdominal pain or digestive bleeding; 94.1% of tumors expressed CD117. Most of them were discovered while performing a laparotomy or ultrasound scan; 94.1% of tumors were removed; 35.2% (6 out of 17) of patients suffering from GIST met consensus criteria for aggressive behavior. Over 25.6 months (+/-22.5) metastasis or tumor relapse occurred in 23.5% (4 out of 17) of patients--those with more frequent high-risk criteria, symptomatic and bigger tumors, and tumors not expressing CD117. The three patients with tumor relapse were prescribed imatinib mesylate. Three patients died because of the tumor, and four from other causes unrelated to GIST. GIST was diagnosed in around 12 cases per million a year. Its diagnosis was usually an incidental finding during a medical evaluation, and tumors were malignant in nearly one fourth of cases. We can predict its outcome depending on different aspects.