ESTRO 2021 Abstract Book

S757

ESTRO 2021

time between the end of RT and last follow-up was 27,9 months. Most patients were male (n=30). The mean age was 56 years (range 41-68 years). Thirty-three patients (94,3%) had good performance status (PS-ECOG 0). BCLC stage was 0 in two patients, A in 26 and B in 7. Most patients were in Child-Pugh class A (n=26), and nine were in Child-Pugh class ≥ B7. Considering the ALBI score, thirteen patients had grade 1, nineteen had grade 2, and three had grade 3. In terms of multifocal disease, two patients had three lesions, and nine patients had two. All the others had a single lesion. The mean lesion size was 25 mm (range 7-57 mm). Most lesions were located in the right lobe (n=31), and only one was located in the caudate lobe. SABR was the first-line treatment in 28 lesions (58,3%), while twenty lesions (41,7%) had relapsed after previous treatments, mainly transcatheter arterial chemoembolization (TACE, for 13 out of 20 lesions). Most lesions were prescribed 48 Gy in 3 fractions (n=24) or 40 Gy in 5 fractions (n=20). The mean liver volume receiving more than 15 Gy was 1297 cc (range 730–1504 cc). Local control (LC) rates were 97,5% at 12, 24, and 36 months. Overall survival (OS) rates following LT were 91,3%, 86,2% and 79% at 12, 24 and 36 months, respectively (fig.1).

Progression-Free Survival (PFS) between the end of RT and LT was 79,5% at six months and 49,7% at 12 and 24 months. Every newly detected lesion was intrahepatic extra-field. The mean interval between SABR and LT was 5.9 months (0.0–35,0 months). The mean time between SABR and waiting list entrance was 2.1 months (range 1.2–4.5) for patients bridged to LT, and 3.9 months (range 1.9–5.8), for patients treated with a downstaging aim, respectively. Following LT, Cancer-Specific Survival (CSS) has been 100% at 12 months and 94,4% at 24 and 36 months (fig.2).

Only three major toxicity events (G3-G4) were recorded regarding hematologic toxicity, clinical toxicity, and non-classic radiation-induced liver disease (RILD). Almost all patients (92%) well tolerated SABR. Conclusion SABR proved to be a safe and effective treatment in our case series of HCC patients awaiting transplant.

PD-0916 role of adjuvant chemoradiotherapy in perihilar bile duct cancer C. Lee 1 , K. Kim 2 , H. Kim 3,5 , W. Kwon 3 , J. Jang 3 , K. Lee 4 , D. Oh 4 , K.B. Lee 5 , E.K. Chie 1

1 Seoul National University College of Medicine, Department of Radiation Oncology, Seoul, Korea Republic of; 2 Ewha Womans University College of Medicine, Department of Radiation Oncology, Seoul, Korea Republic of; 3 Seoul National University College of Medicine, Department of Surgery, Seoul, Korea Republic of; 4 Seoul