A multi-institutional epidemiologic and oncologic profile of gastrointestinal stromal tumors in the Lebanese population.

Abstract

e23508 Background: Gastrointestinal stromal tumor (GIST) is a rare type of soft tissue sarcoma that most commonly arises from the gastric mesenchymal cells. This study represents the first GIST registry in Lebanon. The aim of this study is to describe the Lebanese cohort of GIST cases and their management standards in resource-limited setting. Methods: This study is a multi-institutional retrospective study of GIST cases diagnosed at the American University of Beirut Medical Center and Hammoud Hospital University Medical Center between 1996 and 2017. Study objectives included epidemiologic and clinical profiling of patients with GIST, tumor characteristics, approach to diagnosis, evaluation of medical and surgical interventions, and oncological outcomes. Results: The database includes 106 GIST cases with a median age of 63.5 years (24-90) and male predominance of 56.6%. Median tumor size is 6 cm (0.3-21) with the most common presenting symptoms being abdominal pain and anemia. Endoscopy is the most commonly used diagnostic modality (49%) with confirmatory biopsy done in 42% of the cases. The most common tumor location is gastric (56.7%) followed by the small intestine (32.7%) and colon (7.7%). Noteworthy, the most common tumor size in female is between 5-10cm (40%) versus 2-5cm in males (32%). The most common histologic cell type is spindle cell (65.7%) followed by epithelioid and mixed. CD 117 and CD 34 are positive in 91% and 78% of the cases, respectively. Metastasis on presentation is present in 16% of the cases. Only 14.7% of the cases received neoadjuvant therapy in the form of chemo- or targeted therapy while 31% received adjuvant therapy in either form. For the 25% of cases that received adjuvant imatinib or sunitinib, the median tumor size is 8.8cm (4-20cm). Most patients (91%) underwent surgery, either by laparotomy (66%) or laparoscopy (34%). Of those, 97.7% had negative surgical margins. Recurrence occurred in 18.7% of cases with regional and distant recurrence occurring equally (35%) versus local recurrence (30%). Survival analysis shows an overall survival of 87% over a follow up period of 14 years. The 3- and 5-year disease-free survival is 80% and 76%, respectively. Conclusions: Findings from this collaborative study adds to the international epidemiology on GIST. It also shows that GIST features as well as medical and surgical practices in this Lebanese cohort conform with those reported from other populations. GIST histopathological features. Gastrointestinal Stromal Tumor Count Percentage Site of Primary Tumor Gastric 59 56.7 Small Intestine 34 32.7 Colon 8 7.7 Extra-gastrointestinal 3 2.9 Cell Type Spindle 44 65.7 Epithelioid 10 14.9 Mixed 11 16.4 Others 2 3 Cell Biomarkers CD117 85 90.4 CD34 71 78 Metastasis at Presentation Yes 17 16 No 89 84