%0 Journal Article %A G Imseeh %A DPJ Barton %A M Llewelyn %A J Ash %A A Fernandes %A A Taylor %T P103 Feasibility of post-operative stereotactic ablative radiotherapy (SABR) using cyberknife for positive margins after pelvic exenteration for gynaecological malignancy %D 2019 %R 10.1136/ijgc-2019-ESGO.166 %J International Journal of Gynecologic Cancer %P A120-A120 %V 29 %N Suppl 4 %X Introduction/Background Surgical margin status is a strong prognostic indicator of disease free and overall survival following pelvic exenteration (PE) for recurrent gynaecological malignancy. There have been few attempts at post-operative treatment to improve this and intraoperative radiotherapy was associated with high neurotoxicity. We report our preliminary experience of re-irradiation using stereotactic radiotherapy (SABR) to the positive surgical margin using Cyberknife™.Methodology This is a retrospective evaluation of four patients treated at the Royal Marsden Hospital with SABR to the positive margin after pelvic exenteration. Radio-opaque fiducial markers at the positive margin were placed post-operatively in three patients and intra-operatively in one. The Cyberknife system was used for planning and treatment delivery (Abstract P103 figure 1).Patients were followed up at 3 monthly intervals and underwent a clinical examination, documentation of acute and late toxicity, and imaging. Patients also completed quality of life questionnaires including ED-5D-3L and Brief Pain Inventory.Results Median age was 56 years (30–72) and median follow up was 14.3 months. Two patients had an endometrial endometrioid primary, one patient had adenoid cystic carcinoma of the bartholin gland and one had glassy cell carcinoma of the cervix. Three patients had total PE and one had anterior PE. Radiotherapy dose was 30 Gy in 5 Fractions over two weeks prescribed to 70–80% isodose.There were no Grade 3 or 4 acute or late toxicities related to SABR. One patient died of multifocal recurrence, one is alive with pelvic recurrence and two are alive with no disease. There were no recurrences within the radiotherapy field.Conclusion SABR offers an attractive option for complete non-surgical ablation after histopathological assessment of surgical margins. Our early experience shows SABR using Cyberknife to the positive margin after pelvic exenteration is feasible and well tolerated. Work is on-going to determine patient selection criteria and to study efficacy.Disclosure Nothing to disclose.Abstract P103 Figure 1 %U https://ijgc.bmj.com/content/ijgc/29/Suppl_4/A120.1.full.pdf