ESTRO 2021 Abstract Book

S382

ESTRO 2021

Within the Hepatocellular carcinoma (HCC) therapeutic management spectrum, curative therapies include surgical resection, orthotopic liver transplantation (LT), and ablative techniques. Data supporting the role of stereotactic ablative radiotherapy (SABR) as a local ablative option in HCC patients are consistently growing. Herein, we aimed at analyzing its role within this clinical scenario. Materials and Methods 250 patients (366 lesions), who underwent SABR between September 2012 and April 2020 at our Radiation Oncology Department, were included in this efficacy and toxicity retrospective analysis. Results The median follow-up time was 16 months (range 1-88 months). The median age was 70 years (range 28-91 years). Most of the patients were males (76.8%). The 56.8% of patients were classified as early-stage (BCLC A), 26.4% in stage intermediate (BCLC B) and 14.4% in very early stage (BCLC 0). Only six patients presented in the advanced stage (BCLC C). Regarding the ALBI score, 150 patients (60%) were classified as grade 2, while 91 (36.4%) had a grade 1. SABR represented the first-line therapy in 187 HCC nodes (51.1%), while it was a "rescue" therapy for 179 (48.9%) relapsed lesions. In 35 patients, SABR was administered before LT. The median total liver volume was 1384 cc (range 774.60-2896.3 cc). The median volume of the healthy liver was 1294.23 cc (range 634.18-2834.36 cc). The two most frequently used schedules were 48 Gy in 3 fractions (in 48.3% of patients) and 40 Gy in 5 fractions (in 31.1% of patients). The median PTV was 56.86 cm³ (range 5.0-1335.90 cm³). The local control rates (LC) at 12, 24, and 36 months were 93.3% (fig.1). The overall survival rates (OS) were 77.1%, 55.1%, and 43.1%, respectively, at 12, 24, and 36 months from the SABR end (figures 1-2). At the univariate analysis, the patient's age and performance status (PS), clinical stage, Δ- Child, Δ-ALBI score, number of lesions per patient, and radiation-induced liver disease (RILD) were related to survival with statistical significance (fig.2). Multivariate analysis confirmed the statistically significant correlation with OS only for age, PS, BCLC stage, Δ-Child-Pugh, and Δ-ALBI score (fig.2). Two-hundred forty- five patients were evaluable for toxicity, of whom 87.8% (n=215) retained good function liver, with no changes in Child-Pugh from baseline. Regarding the ALBI score, no changes were observed for 179 patients (73.1%). Non-classic RILD was observed in 15 patients (6.1%). There was no statistically significant correlation between RILD and volume of PTV, healthy liver volume, healthy liver volume receiving more than 15 Gy in the case of treatment with 3 fractions or more than 21 Gy in the 5 fractions schedule.

Conclusion SABR proved to be a safe and effective treatment in our case series of HCC patients.

PH-0500 Outcome analysis in locally advanced pancreatic cancer: a predictive model (PAULA-1) A. Arcelli 1,2 , G. Tarantino 2,3 , M. Buwenge 1,2 , G. Macchia 4 , F. Bertini 1,2 , A. Guido 1 , F. Deodato 4,5 , S. Cilla 6 , V. Scotti 7 , M.E. Rosetto 8 , I. Djan 9 , S. Parisi 10 , G.C. Mattiucci 5,11 , F. Cellini 5,11 , M. Fiore 12 , P. Bonomo 13 , L. Belgioia 14 , R.M. Niespolo 15 , P. Gabriele 16 , M. Di Marco 2,17 , N. Simoni 18 , R. Mazzarotto 18 , A.G. Morganti 1,2 1 Radiation Oncology, IRCCS Azienda Ospedaliero-Universitaria di Bologna, Bologna, Italy; 2 Department of Experimental, Diagnostic, and Specialty Medicine (DIMES), Alma Mater Studiorum Bologna University, Bologna, Italy; 3 Dana Farber Cancer Institute, Harvard Medical School, Boston, USA; 4 Radiation Oncology Unit,