ESTRO 38 Abstract book

S777 ESTRO 38

responses, local control rate, overall survival and toxicities were evaluated. Results Mean dose of biological effective dose (BED) with α/β = 10 Gy delivered by IG‐IMRT group was 67.23 ± 8.48 Gy vs. 63.43 ± 5.01 Gy (p = 0.008) by non‐ IGRT group. The objective response rates (ORR) of IG‐ IMRT vs. non‐IGRT was 95.3% vs. 80.9% (P = 0.085). The actuarial local control rate of IG‐IMRT vs. non‐IGRT was 74% vs. 52.3% at one‐year, and 69% vs. 47% at two‐year. (p = 0.019) , which showed the advantage of IG‐IMRT. Longer median overall survival was found in IG‐IMRT group (15.3 months) than that in non‐IGRT group (9.7 months), (p = 0.098). One‐year overall survival of IG‐IMRT vs. non‐ IGRT was 69% vs. 38.1%, (P = 0.006). However, two‐year overall survival of them was 19.3% vs. 14.5% (p = 0.066) with p‐value was 0.098 which indicated no superiority of long‐term survival of IG‐IMRT. Number of lymph node ≥ 2, previous treatment without surgery were negative independent prognostic factors, while BED 10 ≥ 65 Gy was a protective factor. Toxicities were mild for both groups while IG‐IMRT showed less late hepatic toxicity. Conclusion Dose delivered by IG‐IMRT is slightly higher which appears to be more effective and shows a superiority of short‐term survival and local control rate in HCC patients with LNM. EP-1430 Can SBRT improve the prognosis of unresectable pancreatic cancer? Clinical results on 106 patients T. Comito 1 , C. Franzese 1 , E. Clerici 1 , P. Navarria 1 , G.R. D'Agostino 1 , S. Carrara 2 , L. Rimassa 3 , S. Tomatis 1 , A. Zerbi 4 , M. Scorsetti 1 1 Humanitas Research Hospital, Radiotherapy and Radiosurgey, Rozzano Milan, Italy ; 2 Humanitas Research Hospital, Gastroenterology, Rozzano Milan, Italy ; 3 Humanitas Research Hospital, Oncology, Rozzano Milan, Italy ; 4 Humanitas Research Hospital, Pancreatic Surgery, Rozzano Milan, Italy Purpose or Objective Pancreatic cancer is characterized by a poor prognosis. Surgery is the gold standard of care, however more than 50% of patients are unresectable at the time of diagnosis. In patients with locally advanced pancreatic cancer (LAPC), the integration of chemotherapy (CT) and chemo‐radiation treatment (CRT) is the current therapeutic option, associated with a significant toxicity rate and with a disappointing overall survival (OS). In the last years, the role of stereotactic body radiotherapy (SBRT) in the treatment of LAPC was investigated. Higher local control related to the high doses employed, short overall treatment time and sequential integration with systemic therapy, represent the crucial advantages of SBRT over conventional CRT. Objective of this study is to assess the efficacy of SBRT in patients with inoperable LAPC. Material and Methods Patients with unresectable LAPC with maximum tumor diameter ≤ 5cm, without limph node disease and without distant metastasis were treated with SBRT, after multidisciplinary board evaluation. Prescription dose was 45Gy in 6 fractions. Primary end‐point was freedom from local progression (FFLP). Secondary end‐points were overall survival (OS), progression‐free survival (PFS) and toxicity. Local control (LC) was defined according to RECIST v1.1 criteria. Acute and late toxicity was scored according to the NCI Common Terminology Criteria for Adverse Events (CTCAE) v3.0. Results Between January 2011 and December 2017, 106 patients (49 male‐57 female) with LAPC were treated with SBRT at Humanitas cancer Center. Median age was 68.5 years (range 41‐88 years). 58 patients (55%) received CT before SBRT, for a median time of 5 months (range 3 ‐ 10

In DE cohort, 1‐year LC (local control) and LRC (loco‐ regional control) were 45.5% (SD:9.7;95%CI:26.3‐62.9) and 32.58% (SD:8.9;95%CI:16.5‐50.1). One‐year DFS (disease‐ free survival), CSS (cancer‐specific survival) and OS (overall survival) were 25.5% (SD:8.3;95%CI:11.3‐42.4), 45.1% (SD:9.6;95%CI:26.1‐62.4) and 40.6% (SD:8.9%;95%CI:23.3‐57.3), respectively. For patients who underwent a trimodality strategy, 1‐year LC and LRC were 77.6% (SD:8.6;95%CI:55.2‐89.8) and 59.4% (SD:10.1;95%CI:37.2‐76.0), respectively. Finally, 1‐year DFS, CSS and OS were 45.5% (SD:9.5;95%CI:26.5‐62.7), 72.3% (SD:8.5;95%CI:51.7‐85.3) and 60.7% (SD:8.6%;95%CI:41.8‐75.2). Conclusion Our retrospective clinical and dosimetric data show the feasibility of VMAT in the DE and PO treatment of oesophageal cancer patients for both SCC and adenocarcinoma histology, with a mild toxicity profile and robust dosimetric results for both target coverage and sparing of organs at risk. EP-1429 IG-IMRT improves short-term survival for lymph node metastases from hepatocellular carcinoma Z. Haige 1,2 , S. Jing 1 , C. Yixing 1 , Z. Zhaochong 1 1 Zhongshan Hospital- Fudan University, Department of Radiation Oncology, Shanghai, China ; 2 Luoyang Central Hospital, Department of Radiation Oncology, Luoyang, China Purpose or Objective To evaluate the responses and toxicities in hepatocellular carcinoma (HCC) patients with abdominal lymph node metastasis (LNM) treated with either Image‐guided Intensity‐ modulated radiotherapy (IG‐IMRT) or non‐IG‐ IMRT. Material and Methods We retrospectively reviewed 85 HCC patients with regional LNM treated with IG‐IMRT or non‐IG‐IMRT (including IMRT and 3D‐CRT) according to patients’ intention at our institution between 2011 and 2016. They were identified as HCC by clinical diagnosis with LNM appeared synchronously or metachronously at the confirmation of HCC. The radiation dose to GTV arranged 44.3 to 75.9 Gy, which was limited by Organ At Risk (mainly limited by gastrointestinal tract). The tumor