P-OGC67 Gastric GISTs: Can presentation, Location and Radiological Features predict behaviour? – Experience in a UK cohort

Abstract Background Gastrointestinal stromal tumours (GISTs) most commonly arise in the stomach, vary significantly behaviour and can be difficult to risk stratify accurately pre-operatively. They are increasingly being identified incidentally during endoscopies or cross-sectional imaging. have malignant potential but from very low high-risk. Pre-operatively, histological diagnosis achieved by performing endoscopic ultrasound (EUS) guided fine-needle aspirate biopsy, samples often contain insufficient material. This study aims assess other features help identify aggressiveness of GISTs pre-operatively guide management decisions. Methods is a retrospective cohort analysing patients treated surgically for GIST 2011-2020 at UK tertiary centre. Exclusion criteria were non-gastric who received different post-operatively. Hospital electronic patient record e-noting systems used collect data. Risk groups stratified according NCCN classification GIST. ‘Very risk’ ‘low combined analysis form ‘lower group; ‘moderate ‘high categories ‘higher group. Statistical analyses conducted using STATA version 15. Results 171 included total. OGD diagnosed gist on histology if ulcerated 14.7% cases. EUS biopsy was performed 39% cases – 84.6% these diagnostic. There higher proportion GOJ/cardia region than lower (16.2% versus 6.7%), though this did not reach statistically significance (p = 0.32). A greater irregular outline (p=.26), heterogenous 0.003) necrotic 0.001) tumours. In addition, more likely exophytic tumours, which endophytic 0.05). ROC curve including all variables had an AUC 0.8971. Conclusions largest gastric population. found that irregular, study, arose GOJ/cardia. keeping with muscularis origin, poor diagnostic tool unless ulcerated. FNA biopsies much rate confirmation. knowledge might facilitate individualised approach non-operative surveillance expedited surgery lesions.