ESTRO 2020 Abstract book

S618 ESTRO 2020

2-year local failure rate was 10% (1-27%). There were 2 cases with grade 3 liver toxicity and 2 cases with grade 3 skin toxicity observed. Of the 2 cases with liver toxicity, one suffered multiple intrahepatic relapses and deceased after 5 months because of that, and the other suffered cerebral infarction and deceased after 10 months because of that. No grade 4 or severe toxicity was observed Conclusion With respect to the very limited nature of this study, CIRT does appear to be effective and safe in treating advanced HCC. Confirmation through prospective studies is to be done. PO-1078 Long survivors’ nature of pancreatic cancer treated with chemoradiotherapy using photon or proton Y. Hiroshima 1,2 , N. Fukumitsu 3 , T. Saito 4 , H. Numajiri 1 , K. Murofushi 1 , K. Ohnishi 1 , M. Mizumoto 1 , K. Nakai 1 , H. Ishikawa 1 , T. Okumura 1 , H. Sakurai 1 1 Faculty of Medicine- University of Tsukuba, Radiation Oncology & Proton Medical Research Center, Tsukuba, Japan ; 2 University of Tsukuba Hospital, Radiation Oncology & Proton Beam Therapy Center, Tsukuba, Japan ; 3 Kobe Proton Center, Radiation Oncology, Kobe, Japan ; 4 Ibaraki Prefectural Central Hospital, Radiation Oncology, Kasama, Japan Purpose or Objective We reported good clinical outcome and low toxicity of proton beam therapy (PBT) for unresectable locally advanced pancreatic cancer (LAPC). And we found dose escalation was one of the most important factors to prolonged local control (LC) and overall survival (OS). The purpose of this study is to investigate characteristics of long survivors of LAPC treated with photon radiotherapy or PBT. Material and Methods A total 67 LAPC patient cases (38 male and 29 female, 36- 83 years old) treated with concurrent chemoradiotherapy (CCRT) with photon radiotherapy or PBT between November 2005 and March 2016 were retrospectively reviewed. 25 patients received photon radiotherapy and 42 others received PBT. All patients received photon radiotherapy and 12 received PBT was treated on a conventional 50 Gray (Gy) or 50 Gray Equivalents (GyE) in 25 fractions protocol and 30 others treated on 54.0- 67.5GyE in 25-33 fractions. We defined long survivors as patients who live or dead after more than 24 months from period when CCRT started. There were 16 long survivors of 67. Gemcitabine or S-1 (Tegafur, Gimeracil and Oteracil) was used concurrently. 35 patients received hyperthermia concurrently. Toxicity, OS, LC and correlation factors with long survivors were examined. Results A total of 23 patients were alive and 44 remaining patients had died of pancreatic cancer. The follow-up period range was 1.27-60.87 (median: 13.0) months. Acute adverse events more than grade3 was observed in 24 patients of 1 gastric ulcer and 23 hematologic events. Late adverse events more than grade3 was observed in 1 of small intestine ulcer. In PBT group, the 1-year/ 2-year OS and LC rates were 77.8/50.8% and 83.3/78.9% with median survival time (MST) of 25.6 months, and photon radiotherapy group, the 1-year/ 2-year OS and LC rates were 67.1/11% and 49.2/0% with MST of 15.7 months. PBT, total irradiation dose and hyperthermia showed significant correlation with long survivors (p=0.031, <0.001 and 0.049). Conclusion PBT could prolonged survival periods safely with dose escalation. Dose escalation with PBT and hyperthermia may contribute to long-term survival.

OS by Treatment/RE HISP

AS

NANH p

All

42.6

66.2

27.2 <.0001

not reached at 84m

not reached at 84m

NAC

38.4 0.0664

NACRT

45.4 57.9

36.4 49.0

35.7 0.7282 32.6 0.0220

Adj Chemo

Conclusion These findings suggest significant heterogeneity amongst different RE populations with GAC which can potentially translate to the need for different treatment regimens. Future prospective trials should aim to recruit diverse patient populations more representative of global disease burden. Study limitations are its retrospective nature, incomplete chemotherapy information in SEER, and lack of disease specific outcomes data in the NCDB. PO-1077 Carbon-ion radiotherapy for hepatocellular carcinoma with vascular invasion H. Makishima 1 , S. Yasuda 2 , H. Kato 3 , T. Kaneko 1 , H. Sato 1 , T. Chang 1 , G. Kasuya 1 , S. Yamada 1 , H. Tsuji 1 1 National Institutes for Quantum and Radiological Sciences and Technology, QST Hospital, Chiba City- Inageku, Japan ; 2 Chiba Rosai Hospital, Department of Radiology, Ichihara City, Japan ; 3 Kato Medical Clinic, Kato Medical Clinic, Tokyo, Japan Purpose or Objective While treatment outcomes for early to mid-stage HCCs are generally satisfactory, those with vascular invasion or major bile duct invasion have a limited prognosis of less than 12 months MST and is an unmet medical need. We aimed to evaluate the efficacy and safety of carbon-ion radiotherapy (CIRT) for those with massive vascular or bile duct invasion by retrospectively analyzing cases treated at our facility. Material and Methods All cases treated by CIRT at National Institutes of Radiological Sciences upto April 2019 were included in this study. Of which those matching the following criteria were analyzed. Evidence of vascular invasion to primary branch of the portal vein or major hepatic veins, or invasion to main hepatic ducts, and, treated by 45-48 Gy (RBE)/2Fr or 52.8-60 Gy (RBE)/4Fr, which are doses confirmed to have a 3-year control rate of approximately 90% or at higher doses, and, treated by a curative intent. Follow-up was done every 3 months after treatment by CT or MRI. Patients who were not followed up in person, were contacted annually by mail. Missing data from patients were supplemented from the Japanese family registry system, a nationwide registry that includes date and cause of death, and issuer of the death certificate. Local failure was defined as interval regrowth or emerging of APHE. All toxicities were evaluated by CTCAE v5.0. Overall survival and progression-free survival was evaluated by Kaplan-Meier estimator and local failure rate by Gray analysis with death and initiation of systemic therapy as a competing risk. All statistical calculations were performed using R. Results From 1994 to 2019, 633 cases were treated for HCC. 402 cases were treated by 45-48 Gy (RBE)/2Fr or 52.8-60 Gy (RBE)/4Fr. Out of this, 35 were identified with a vascular or bile duct invasion to a major branch or further. 27 cases were treated by a curative intent and were analyzed. Three cases only had hepatic duct invasions lacking vascular invasions. Background liver function ranged from 6-9 in Child-Pugh score with a median of 6. One had BCLC Stage A, 2 Stage B, and 24 was Stage C. With a median follow-up of 20 months, 2-year overall survival was 51% (29-70% 95%CI) with an MST of 27 months (12-45 months). 2-year progression-free survival was 22% (9-39%) and the