ESTRO 2023 - Abstract Book

S1080

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ESTRO 2023

1 Seoul National University Hospital, Radiation Oncology, Seoul, Korea Republic of

Purpose or Objective The aim of this study was to evaluate efficacy and safety of 10-fraction image-guided hypofractionated RT for HCC with Portal vein tumor thrombosis (PVTT). Materials and Methods A total of 50 patients who underwent hypofractionated RT for HCC with PVTT between 2016 and 2022 were recruited for the single institution cohort. The median prescribed dose of 50 Gy (range, 40-50 Gy, BED10 ; 56-75 Gy10). was delivered in 10 fractions in all patients. Follow-up imaging was performed at 3 months-interval after the completion of RT. The extent of PVTT was described according to the Liver Cancer Study Group of Japan classification: Vp0 = no PVTT, Vp1 = segmental portal vein branch, Vp2 = right/left anterior/posterior portal vein, Vp3 = right/left portal vein and Vp4 = main portal vein. Response evaluation was performed using response evaluation criteria in solid tumors, version 1.1. Freedom from local progression (FFLP), progression-free survival (PFS), and overall survival (OS) were calculated from the start date of RT. Results In this cohort, 4% of patients had Vp1 PVTT, 18% had Vp2, 38% had Vp3, and 40% had Vp4. The median PTV volume was 120.1 cc (interquartile range [IQR], 69.2-192.5 cc). Thirty-six (72%) patients received 50 Gy in 10 fractions. With a median follow-up of 11.1 months (IQR, 3-30 months), the median OS was 18.5 months, and 1-year FFLP, PFS, and OS rates were 91.5%, 25.4%, and 61% respectively. At 3 months after RT, 16% had a complete response, 22% had a partial response, 56% had a stable disease and 6% had a progressive disease. In the multivariate analysis, PTV volume ≥ 170 cc (hazard ratio [HR] 2.86, p=0.02), AFP ≥ 600 IU/ml (HR 3.17, p <0.01), Vp3 or Vp4 (HR 4.06, p=0.03), tumor multiplicity (4.95, p<0.01) were significantly related to OS. During the follow-up period, there were 2 (4%) cases of grade ≥ 3 toxicity: grade 3 AST/ALT elevation (n=1), and acute cholangitis (n=1).

Table1 . Radiologic response evaluation Response 3 months 6 months 9 months 12 months CR 8 (16.0%) 12 (36.4%) 11 (42.3%) 10 (47.6%) PR 11 (22.0%) 3 (0.9%) 2 (7.7%) 3 (14.3%) SD 28 (56.0%) 15 (45.4%) 12 (46.2%) 7 (33.3%) PD 3 (6.0%) 3 (0.9%) 1 (0.4%) 1 (0.5%) Total 50 33 26 21