EP061/#647 Effect of the extent of radical excision on clinical outcomes after radical hysterectomy for early-stage cervical cancer: a meta-analysis

Abstract

Methods Scans from 20 patients with pelvic recurrence were used, delivering EBRT 45Gy/25 fractions to pelvis followed by SBRT boost. Cumulative dose limits for bowel, bladder, sigmoid, rectum and sciatic nerve were converted to 5 and 10 fraction equivalent constraints. For isotoxic planning, prescription was escalated/de-escalated until any OAR dose constraint was exceeded. Feasible tumour doses (EQD210) with 5 and 10 fractions were compared. Results With conventional VMAT 20 Gy in 10 fractions, median GTV and PTV dose was 20.0Gy (total EQD210 64.2Gy). Using isotoxic SBRT planning for central pelvic disease, median PTV dose (EQD210) was 29.9Gy (total 74.1Gy) with 5 fractions compared to 32.9Gy (77.2Gy) with 10 fractions and GTV 30.8Gy (cumulative 75Gy) versus 33.9Gy (cumulative78.1Gy) (p<0.0001). Similarly, with pelvic sidewall disease isotoxic doses were increased with 10 fractions: PTV 42.2Gy (cumulative 86.4Gy) versus 45.5Gy (cumulative 89.7Gy); GTV 45Gy (cumulative 89.2Gy) versus 48.6Gy (cumulative92.9 Gy) (p<0.0001) Conclusions Longer fractionation can significantly increase deliverable tumour doses. Further investigation is required to determine optimal patient specific regimens.