ESTRO 2020 Abstract Book

S562 ESTRO 2020

PO-1059 Definite chemo-radiotherapy with dose- escalation to patients with esophageal cancer M. Nielsen 1 , E. Holtved 2 1 Odense University Hospital, Laboratory of Radiation Physics, Odense, Denmark ; 2 Odense University Hospital, Department of Oncology, Odense, Denmark Purpose or Objective The optimal radiation dose in definite chemo-radiotherapy (CRT) of inoperable, unresectable and recurrent esophageal cancer remains contested, yet still highly relevant in connection with new trials concerning e.g. immuno-radiotherapy and proton therapy. In the literature doses from 50 Gy to 65 Gy are most commonly reported. Here we report the outcome of a cohort of patients treated All patients with inoperable, unresectable and recurrent esophageal cancer (total 90) treated with definite radiotherapy up to 60 Gy according to local guidelines between 2007 and 2013 were included; see table for key characteristica. The planned doses were 59.4-60 Gy/30- 33F to the GTV, while a CTV constructed as the GTV plus 3 cm along the esophagus expanded by 1.5 cm radially received 50-50,4 Gy/28-30 F. Treatment technique was 3D conformal (3 patients) or IMRT/VMAT (87 patients) with either a final boost or a simultaneous integrated boost. Most common chemoregimes were Cisplatinum+5FU (46 pts) and 5-FU (24 pts). Patient charts were consulted for recurrences and death. Dose and volume parameters were extracted from the treatment planning system. at a single institution. Material and Methods

years DFS was 25% in pts with ILBT and 20% in group of pts without ILBT (p=0.7913). The two-years OS was 35% in pts with ILBT, however, among pts without ILBT 2-years OS was 28% (p=0.5284 ). Conclusion Our analysis showed that adding brachytherapy to EBRT as a boost contributed to better local control in these pts, with comparable late toxicity, however, without improving of DFS and OS. PO-1058 Proton beam therapy for hepatocellular carcinoma of caudate lobe T. Iizumi 1 , T. Okumura 1 , Y. Sekino 1 , H. Numajiri 1 , M. Mizumoto 1 , K. Nakai 1 , H. Ishikawa 1 , H. Sakurai 1 1 Tsukuba University, Radiation oncology, Tsukuba, Japan Purpose or Objective Hepatocellular carcinoma (HCC) originating from the caudate lobe of the liver (caudate HCC) is rare, and local curative treatments like surgery or RFA are technically challenging because the lobe is so deeply seated between IVC and hepatic hilum. As a result, achievement of tumor clearance is difficult and higher recurrence rate was reported compared with HCC in other segments of the liver. Although chemoembolization is also applicable for caudate HCC, local recurrence rate of chemoembolization has been higher than that of other treatment modalities. The role of proton beam therapy (PBT) in the treatment of HCC has been expanding with several reports about its high local control rates while minimizing radiation hepatotoxicity. However, few reports have focused on the clinical outcomes of proton beam therapy (PBT) for caudate HCC. Therefore we sought to analyze the clinical outcomes of PBT for caudate HCC to assess the efficacy and toxicity of this treatment modality. Material and Methods This is a single institutional, retrospective study of caudate HCC patients who received PBT between 2002 and 2014. 30 patients received definitive treatment among a total of 52 patients with caudate HCC and were included in this study. Overall survival (OS), local control (LC) and progression- free survival (PFS) were estimated by Kaplan- Meier method. Univariate and multivariate analyses for OS was assessed using Cox proportional hazard model. Toxicities were classified using the National Cancer Institute’s Common Terminology Criteria for Adverse Events version 4.0. Results The median follow-up period was 37.5 months. The median age was 67 (range, 50-83) years old. The composition of sex was male dominant (n=26, 86.7%). 24 patients (80.0%) were classified as Child A, 4 (13.3%) as Child B, and 1 (3.3%) as Child C. The median size of tumor was 2.3 (range, 1.0- 9.0) cm. The majority (n=23, 76.7%) of patients had solitary tumor, while seven patients had multiple tumors (n=7, 23.3%). Five patients had invasion to vessels including major branch of portal vein (n=3, 10.0%) and inferior vena cava (n=2, 6.7%). The median value of AFP was 26.5 (range, 1.0-16861.3) ng/mL and that of DCP was 59.0 (range, 11-16890.0) mAU/mL. Most patients (n=21, 70%) received PBT with 72.6 GyE/22 fractions (fx). Other patients received with 55 GyE/10 fx (n=1, 3%), 60 GyE/15 fx (n=1, 3%), 74 GyE/37 fx (n=5, 17%), or 77 GyE/35 fx (7%, n=2). OS rates at 1, 3 and 5 years were 86.6%, 62.8% and 46.1%. LC rates were 100.0%, 85.9%, 85.9%. PFS were 65.0%, 27.5%, 22.0%. Child A (HR 4.83, 95% CI: 1.52-15.4, P < 0,01), single tumor (HR 3.73, 95% CI: 1.28-10.91, P = 0.02) and lower serum AFP level (HR 4.07, 95% CI: 1.52- 10.92, P < 0.01) were significant factors in longer overall survival. No grade 3 or worse acute and late toxicity was observed. Conclusion PBT was effective and tolerable for caudate HCC.

Results Median volume of GTV was 24.4cm3 (range 3.5-122.1cm3), and the median volume of the low dose PTV was 392.0cm3 (range 187.5-927.2cm3). Median Mean Lung Dose (MLD) was 11.9 Gy (range 3.7-20.4 Gy). Median overall survival (OS) was 21 months, with 3 year survival 34% and 5 year survival 26%. Median local recurrence free survival was 50 months, with 48% of the patients free from local recurrence at 5 years. Kaplan Meier plots are in the figure, parts A) and B), respectively. In our study no patients had a local recurrence later than 50 months after RT. In univariate analysis, performance status (p=0.01), gender (p=0.01) and number of symptoms at referral (p=0.001) were statistically significant factors for survival. In a backward stepwise conditional Cox regression analysis the same 3 factors as well as MLD contained prognostic value.