ESTRO 2022 - Abstract Book

S86

Abstract book

ESTRO 2022

Conclusion In this nationwide cohort, predictive factors for ILR are vascular resection, absence of lymph vascular invasion, perineural invasion, N2 lymph node status, R1 resection margin status, and omission of adjuvant chemotherapy.

OC-0112 Feasibility and safety of daily adapted MR-guided SABR for pancreatic cancer in the UK

J. Good 1 , B. George 2 , S. Teoh 3 , A. Gaya 1 , R. Owens 3 , L. Aznar Garcia 1 , M. Robinson 4 , A. Martin 1 , K. Chu 4 , S. Mukherjee 3 , T. Maughan 3 1 GenesisCare, Radiation Oncology, Oxford, United Kingdom; 2 GenesisCare, Medical Physics, Oxford, United Kingdom; 3 University of Oxford, Institute for Radiation Oncology, Oxford, United Kingdom; 4 Oxford University Hospitals, Department of Oncology, Oxford, United Kingdom Purpose or Objective Report the successful completion of a UK-based Compassionate Access Programme to provide daily adapted MR-guided (MRgRT) stereotactic ablative radiotherapy (SABR) for pancreatic cancer, including patient selection criteria, planning approach and tumour characteristics. Demonstrate the dosimetric benefits of MRgRT and report acute toxicity rates in this cohort. Materials and Methods Eligibility included patients with borderline resectable, locally advanced, medically inoperable, and locally recurrent disease; good organ function; ECOG PS 0-2; and no frank luminal invasion. For each treatment course dosimetric data was available from baseline treatment plans calculated on the anatomy at simulation; predicted doses from the baseline plan calculated on the daily anatomy; and treatment plans based on daily anatomy. UK SABR Consortium organ at risk (OAR) constraints were used alongside those accepted internationally. All patients were offered an online system to collect patient reported outcome measures (PROMs). Results Fifty patients were accepted for treatment following multidisciplinary team review. Median age was 71 (max 89, minimum 40) and 28/50 (56%) were male. The most common (46/50, 92%) prescription dose was 40 Gy in 5 fractions on alternate days. Median GTV volume was 49.6 cc (min 12.7 cc, max 273.1 cc). Forty-nine patients completed treatment. The rate of grade 3+ acute toxicity was 10%. Late toxicity, local control and survival outcomes will be reported.