Gastric GIST

Abstract

Gastrointestinal stromal tumor (GIST) is the most common mesenchymal tumor of the gastrointestinal tract. The stomach is considered the most common site of GIST, and the most common histopathological type of GISTs is spindle cell. Mutational analysis may help in defining the management of GIST. Multiple stratification modules are available for the estimation of GISTs’ prognosis. Surgery is considered the only curative option for GISTs. The discovery of KIT protein has allowed better identification of GISTs and has allowed creation of selective tyrosine kinase inhibitors which dramatically affected GIST management. Results of trials on neoadjuvant imatinib therapy are promising. Adjuvant imatinib therapy is recommended for 3 years and has proven to improve outcome in high-risk GISTs. New therapeutic agents are now available in case of imatinib resistance. Follow-up of patients with GISTs depends on the type of GIST. This trial compared 36 versus 12 months therapy of adjuvant imatinib (400 mg daily) in 400 patients with a high-risk-resected GIST with a median follow-up of 54 months. A high-risk GIST was defined as a tumor size of >10 cm, a mitotic count of >10/50 high-power fields (HPF), a tumor size of >5 cm with a mitotic rate of >5/HPF, or a tumor rupture. About 50% of the patients had gastric GIST in this study. The study reported prolonged 5-year RFS and OS rates for patients assigned for 36 months imatinib adjuvant therapy compared with patients assigned for the 12-month group, 65.6 versus 47.9% and 92% versus 81.7%, respectively. The results of this trial resulted in NCCN guidelines recommend ing adjuvant imatinib for at least 3 years for patients with intermediate or high risk of GIST recurrence [90 In a latter follow-up report for the trial with a median follow-up of 90 months, patients assigned to a 3-year group a persistent favorable outcome greater RFS versus 52% and overall (92 versus 85%) 91].