ESTRO 37 Abstract book

S750

ESTRO 37

Material and Methods We retrospectively analyzed the patients with LD-SCLC who underwent RT as curative aim at single institution from January 2004 to December 2015. Median radiotherapy dose was 52.5 Gy for 25 fractions. Locoregional progression-free survival (LPFS), progression-free survival (PFS), and overall survival (OS) were assessed, and patterns of failure and prognostic factors were evaluated. Results A total of 372 patients were included in the analysis. A median follow-up period was 19 months (range, 2-146 months) and the median age at the time of diagnosis was 62 years (range, 32-83 years). Only 43 patients (12%) was woman and 319 patients (86%) had clinical stage Ⅲ disease. A quarter of patients received sequential CRT, but the others were fitted for concurrent CRT. In concurrent CRT group, radiotherapy started at the 3 rd cycle of chemotherapy in some patients, but the others received concurrent CRT from the beginning. The 5-year LPFS, PFS, and OS were 45%, 23%, and 26%, respectively. A total of 81 patients (22%) experienced local progression as first site of failure, although distant metastasis was more common. For those who received prophylactic cranial irradiation (PCI) (160 patients, 43%), PFS, frequency of brain metastasis, and OS were improved. On multivariate analysis, concurrent CRT, clinical stage, and PCI were statistically significant prognostic factor for OS. Conclusion Concurrent CRT showed better clinical outcomes regardless of the timing of RT than sequential RT. Future investigation for the dose-escalation of in-house radiotherapy dose should be considered. EP-1374 SBRT for new lesions after surgery or curative intended radiotherapy in patients with NSCLC O. Hansen 1,2 , C. Kristiansen 1 , S.S. Jeppesen 1,2 , T.B. Nielsen 3 , T. Schytte 1 , M. Nielsen 3 1 Odense University Hospital, Dept. Oncology, Odense, Denmark 2 Odense University Hospital, Academy of Geriatric Research AgeCare, Odense, Denmark 3 Odense University Hospital, Laboratory of Radiation Physics, Odense, Denmark Purpose or Objective Stereotactic Radiotherapy (SBRT) is an efficient treatment for early stages of inoperable NSCLC, but may also be used when new tumors arise after previously curatively intended by surgery or radiotherapy (RT). The aim of this study was to study the outcome of SBRT in these situations Material and Methods All cases of NSCLC treated with SBRT at our institution are prospectively recorded. From July 2009 to December 2016 137 patients previous treated with curatively intend with either surgery or RT had SBRT for new lesions. The doses used for peripheral located tumors were 45-66 Gy (central doses) in 3 fractions (F) while the doses for centrally located tumors were 45 Gy/10 F, 50 Gy/5 F and 80 Gy/8 F. The SBRT technique was either IMRT or VMAT. 97 patients previously had surgery (S-Grp): Resection 23 (24%), lobectomy 67 (69%), bi-lobectomy 1 (1%), or pneumonectomy 6 (6%). 40 patients had previously RT (RT-Grp): SBRT 25 (62.5%) or conventionally fractionated RT 15 (37.5%). All patients had more than 10 months (mo.) of potential follow-up. Overall survival was calculated from day one in the treatment of the new lesion

differentiation of doses, narrow margins, sparing of the ipsilateral lung and following from this exceeding the pulmonary QUANTEC-criteria with a low grade of toxicity. Using the same dose scheme with VMAT possible advantages are higher conformality in regions with medium and high dose. Therefore the question arise compared “Target Splitting” does the use of VMAT result in higher toxicity? Material and Methods At the most of 7days after two cycles of chemotherapy radiotherapy is initiated by application of following doses: primary tumor 73.8 Gy up to 90 Gy (with positive correlation to the tumor volume), macroscopically affected lymph nodes (LN) 61.2 Gy, elective LN 45 Gy (approximately 6 cm cranial from last macroscopically affected LN). Fractionation: 1.8 Gy twice a day, with an interval of at least 8 hours. Margins GTV (ITV) -> PTV: 7 mm. IGRT is made with a cone beam CT before each fraction and matched to the primary tumor. All patients received the prescribed dose according to the protocol. Acute toxicity was evaluated according to CTCAE 4.03. Results 31 patients with histologically proven locally advanced NSCLC were treated from 01/2015 to 06/2017 (4/6/16/5 patients with stadia IIB/IIIA/IIIB/IIIC , 8th edition UICC). 29 % of the patients had weight loss of > 5% three months before diagnosis, and 23 % had a Karnofsky performance score of < 80 % at start of therapy. Pulmonary V20 on both sides 27 % (median, range 4 – 53 %), V5 on both sides 48 % (median, 14 – 99 %), Dmean 14 Gy (3.8 – 26 Gy). In 7/31 cases (23 %) the QUANTEC constraints V20 (35 %) and in 2/31 cases (6 %) the Dmean (23 Gy) could not be respected. Median follow-up of all patients was 9.3 months (range 2.3 – 29.9). Acute side effects (up to 6 months post RT): pulmonary grade 1/2/3 in 1/4/1 cases; esophageal grade 1/2/3 in 8/18/1 cases; no grade 4/5 toxicities. Late side effects (> 6 months post RT): one therapy- related lethal hemorrhage cannot be excluded. Apart from that no late toxicities > grade 1 were observed so far. One year survival rate 74 %, median survival duration is not yet reached. Local-/regional tumor control rate after one year: 88/85 %. Conclusion 91 % of all patients with locally advanced NSCLC were treated according to the DART-bid protocol with VMAT. Despite application of high doses acute toxicity is low to moderate. A longer observation period is necessary for meaningful statements on late toxicity and overall survival. So far VMAT does not increase toxicity compared Target splitting technique and improves the ability of implementing DART-bid concept (sparing of the ipsilateral lung, narrow margins) for a wide range of patients. EP-1373 Role and Timing of Radiotherapy for Limited- Disease Small Cell Lung Cancer M. Koh 1 , S.Y. Song 1 , S.S. Kim 1 , J.H. Kim 1 , S.D. Ahn 1 , S.W. Lee 1 , S.M. Yoon 1 , Y.S. Kim 1 , J.H. Park 1 , J.H. Jung 1 , E.K. Choi 1 1 Asan Medical Center, Radiation Oncology, seoul, Korea Republic of Purpose or Objective To evaluate clinical outcomes of chest chemo- radiotherapy (CRT) in different treatment sequence and to assess the adequacy of current radiotherapy (RT) dose for local tumor control in limited-disease (LD) small cell lung cancer (SCLC).