Risk Stratification (Miettinen) Mutational status results (N=50) Ten year prospective experience of Gastrointestinal stromal tumours (GISTS) from the Cambridge GIST Study Group, United Kingdom V R Bulusu, H Hatcher, R H Hardwick, N Carroll, S Pursglove, V Save, P Safranek, H M Earl. Cambridge University Hospitals, Cambridge UK Background: Cambridge GIST Study Group was formed in 2003. GIST specialist multidisciplinary team (MDT) and GIST clinic were established with central review of histology/radiology and overall management plans. We present 10 year experience of our prospective database which formed the template for the United Kingdom national GIST registry. Methods: All patients who have been referred to the GIST MDT were included in this study. The following data was prospectively collected: Patient demographics *Systemic therapies Presenting symptoms *Surgical interventions GISTS: Site, Size, Mitotic index Mutational status (where available) Risk stratification *Other tumours in GIST pts Histology Spindle cell 84% Mixed 12% Epithelioid 4% Fig 1. Spindle cell GIST Fig 2. Epithelioid GIST Risk Stratification (Miettinen) Very low/low risk 57% Intermediate 16% High 27% Fig 3. Micro GIST Fig 4. Large Gastric GIST Tumour SiteS (Fig 5) Stomach 73% Small bowel 16% EGISTS 4% Colorectal 3% Duodenum 3% Oesophagus 1% Results: 260 pts were reviewed in the GIST MDT. 29 pts had endoscopic/imaging diagnosis of GIST and were not included in the final analysis. 41 pts had other tumours diagnosed when GIST was initially suspected. Histologically confirmed GISTS 190. N= 190 Male: Female 52%:48% Median age 64 yrs (range 14-94) , 4% < 40 years 84% had surgical interventions ( primary or metastases) 9% had resections on Imatinib/Sunitinib Tumour size 0.1-40 cm Ruptured GISTS (spontaneous or intraoperative) 2.6% GIST in Meckel’s diverticulum 1% 14% of GIST pts had other tumours either prior to diagnosis or during treatment/follow up of GISTS Mutational status results (N=50) KIT Exon 11 64% PDGFRA 14% KIT Exon 9 5.5% WILD type 11% KIT Exon 13 5.5% Conclusions: This is the first prospective regional GIST registry data from UK. Our results mirror other large prospective series. GISTS should be managed by an experienced multidisciplinary team to provide a high quality service. vrbulusu@gmail.com