TY - JOUR T1 - EPV224/#620 Radiotherapy for platinum-resistant (PR) ovarian cancer: should this be reconsidered as a standard treatment option? JF - International Journal of Gynecologic Cancer JO - Int J Gynecol Cancer SP - A118 LP - A118 DO - 10.1136/ijgc-2021-IGCS.295 VL - 31 IS - Suppl 4 AU - L Kviat AU - S Banerjee AU - A Taylor AU - A George Y1 - 2021/11/01 UR - http://ijgc.bmj.com/content/31/Suppl_4/A118.1.abstract N2 - Objectives Radiotherapy for recurrent ovarian cancer has traditionally had a limited role due to toxicity, but recent advances enable more targeted treatments. The aims were to evaluate patterns of disease in PR ovarian cancer and investigate feasibility of radiotherapy to treat abdomino-pelvic disease.Methods Gynaecology oncology clinic lists were retrospectively reviewed to identify 50 patients with PR ovarian cancer. Tumour location on imaging at time-point of platinum-resistance was mapped with cumulative incidences by quadrant. Three groups were defined: RT_Feasible - pelvis and lymph nodes; RT_Not Feasible -liver parenchymal metastases, gross ascites, bowel obstruction; RT_Uncertain including peritoneal disease. A dosimetric study was undertaken on ten consecutive RT-Uncertain patients producing IMRT plans delivering 30Gy/10 fractions with pre-defined normal structure dose constraints.Results From 399 patients attending Nov 2019-Feb 2020, 88 (22%) had PR disease, with 63% confined to abdomen-pelvis. Disease was typically multi-focal with involvement of 2 or more quadrants in 84%, and 88% having upper abdominal disease. Group allocation was RT_Feasible 22%, RT_NotFeasible18% and RT_Uncertain 60%. There was median 5 (range 2–9) separate tumour volumes with total volume median 13.6 cm3 (range 6.5–400.3 cm3) resulting in planning target volumes median 458.6 cm3 (243–3077). IMRT plans encompassed tumour volumes while meeting all normal structure tolerances in 50% cases, with all plans failing for planning volumes >1000cm3.Conclusions PR ovarian cancer is often widespread, but radiotherapy was feasible for 52% cases with abdomino-pelvic disease. RT could be integrated into novel treatment strategies for these patients who currently have limited options. ER -