Gastrointestinal stromal tumors (GIST): a single center experience

Abstract

Background: Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal neoplasms of the gastrointestinal (GI) tract. They are believed to originate from the interstitial cells of Cajal (ICCs) or from the precursors of ICCs. Most GISTs show an activating mutation in either the c-kit or platelet-derived growth factor receptor alpha (PDGFRA) gene. Tumor size, mitotic rate, and anatomic location correlate with potential malignancy and recurrence rate.

Patients and methods: A total of 12 patients were diagnosed to have GIST based on histology or immunohistochemistry of a biopsy or resection specimen obtained from the GI tract in the 2004-2009 period. The material was obtained using retrospective data collection.

Results: The male to female ratio was 1:1; mean age 68.2 +/- 7.0 years. The stomach was involved in seven cases (58.3%), the small intestine in four (33.3%), and from a lymph node without the finding of a primary tumor was material obtained in one case (8.3%). The course was asymptomatic in four patients (incidental findings). All 12 patients had surgery; a curative procedure was undertaken in 11 patients. A spindle-cell pattern was present in 8/12 of the specimens examined, epithelioid in 2/12 and a mixed pattern in two cases. Ten specimens were CD117 positive (83.3%), two were negative; all 10 examined specimens exhibited CD34 positivity while two were not examined. The findings were classified as GISTs with a high risk of progressive disease in three patients, with a moderate risk in one patient, and a low or very low degree of malignancy in five patients. GISTs smaller than 2 cm in three patients were regarded as essentially benign. All patients with low and very low risk of progressive disease survive for 1 to 5 years free of signs. Of the three patients with high degree of malignancy, one died within one year for dissemination, the two remaining patients survive for over two years and six month postoperatively on therapy with tyrosine kinase inhibitors.

Conclusion: Tumors classified as GISTs with low and very low risk of progression are associated with a very good prognosis, with virtually all patients surviving 5 years. In patients with high risk or progressive diseases, the prognosis of 5-year survival is much poorer. The main therapeutic option is surgical removal of the tumor (resection or broad excision). Agents showing promise for patients with malignant forms of GISTs are tyrosine kinase receptor inhibitors. Although imatinib is currently used as a first line treatment for all patients with metastatic or unresectable GISTs, it is likely that this treatment will change in the future based on the underlying mutational status.