Hypofractionated radiotherapy to the pancreas: UK experience

525 Background: During the COVID19 pandemic, many centres in the UK, shifted towards utilising hypofractionated radiotherapy (RT) to pancreas. We aim to report the UK experience in hypofractionated radiotherapy to the pancreas in 2020. Methods: We retrospectively identified patients receiving either moderate hypofractionated (15 fractions) or ultra-hypofractionated (3-5 fractions) RT to the pancreas from 7 centres in the UK. Rates of toxicity, progression, death and potential prognostic factors were assessed. Univariate and multivariate Cox proportional hazards analyses were performed. Results: 92 patients from 7 centres were included in the analysis (median age 71 (range 49-88). 90% had performance status of 0-1. 66% had locally advanced disease. 53% had RT delivered over 3-5 fractions (n = 49, median: 30Gy/5f, range:30-40Gy in 3-5f). The rest had 15-fraction RT with or without concurrent chemotherapy (n = 43, median: 45Gy/15f, range: 36-45Gy/15f). Induction chemotherapy (CT) was used in 64% (FOLFIRINIOX –42/59). Median follow-up was 13 months from first treatment (induction CT or RT). Median overall survival (OS) among all patient was 17 months, (95% CI-14.5-19.5 months). On multivariable analysis, induction CT was the only predictor of improved PFS (median survival (MS) 12 vs 5 months; hazard ratio [HR] 0.23; 95% confidence interval [CI]: 0.12-0.44, p < 0.001) and OS (MS 24 vs 11 months; HR 0.15; 95% CI: 0.07 – 0.34, p < 0.001). There were no deaths. 4 patients had grade 3+ toxicities (transaminitis, cholecystitis and gall bladder perforation, small bowel obstruction and diarrhoea) –all had concurrent CT. Conclusions: Our survival outcome appears to be comparable with published data from CT + concurrent chemoradiotherapy. Induction CT appears to improve outcome. Careful selection of patients can help maximise advantage in this patient population.