ESTRO 38 Abstract book

S732 ESTRO 38

therapy forBMs, no extracranial disease, and an NLR of <5.0. Conclusion A low NLR and positive PD-L1 expression independently predict prognosis in patients with BMs from NSCLC after WBRT. These findings suggest that the potential immune response may influence survival among patients with BMs. EP-1337 IMRT/VMAT vs. 3DCRT: the pathological and the clinical outcomes in LANSCLC treated with trimodality S. Appel 1 , Y.R. Lawrence 1 , Z. Symon 1 , O. Haisraely 1 , M. Perlman 2 , E. Ofek 2 , D. Alezra 1 , T. Katzman 1 , N. Honig 1 , M. Ben-ayun 1 , T. Rabin Alezra 3 , S. Dubinsky 1 , J. Kraitman 1 , L. Tsvang 1 1 Chaim Sheba Medical Center, Radiation Oncology, Ramat Gan, Israel ; 2 Chaim Sheba Medical Center, pathology, Ramat Gan, Israel ; 3 Tel-Aviv Sourasky Medical Center, Radiation Oncology, Tel Aviv, Israel Purpose or Objective More advanced radiation techniques, such as Intensity- modulated radiotherapy (IMRT) and Volumetric Arc Therapy (VMAT) are associated with better normal-tissue sparing compared with traditional 3-dimensional conformal radiation (3DCRT). Conversely, these techniques require a high degree of technical expertise and may potentially inadvertently under-dose tumor due to interplay between beam intensity-modulation and tumor movement. We sought to assess the impact of different radiation techniques on pathological and clinical outcomes in non-small cell lung cancer (NSCLC). Material and Methods We conducted a retrospective analysis of LANSCLC patients treated with neoadjuvant chemoradiation followed by surgery between August 2012 and August 2018 at the Sheba Medical Center. We recorded the patient, stage, histology, and treatment details. Radiation dose was prescribed to cover 95% of PTV to high dose (60 Gy); contouring was according to the co- registered PET-CT, without elective nodal irradiation and delivered with daily on-board image guidance (IGRT including KV/KV or CBCT). Primary endpoints were pathologic regression scored according to College of American Pathologists recommendations, as well as the average percent of residual tumor cells. Additional endpoints: surgical margins, the local control rates (LC), disease free (DFS) and overall survival (OS). For the purposes of analysis IMRT and VMAT were combined into a single category. Statistics included non parametric tests, Kaplan Meier estimates; and log rank test Results Our cohort included 74 pts, mean age 65.9 (45-79.7), males in 51/74 (69%) adenocarcinoma in 46/74 (62.1%) squamous in 21/74 (28.3%), stage 3 in 59/74 (79.7%), chemotherapy with platinum-based doublets in 72/74 (97.3%). Radiation dose was 54 Gy and above in 90.5%, mode 59.2Gy. Radiation technique was 3DCRT in 51/74 (68.9%), IMRT in 5/74 (6.7%) and VMAT in 18/74 (24.3%). The use of IGRT-CBCT was in 14/23(61%) in IMRT/VMAT technique, compared to the12/51(23.5%) in 3DCRT p<0.001. Major pathologic response (including pCR and <10% residual cells) was similar between radiation techniques: for 3D: 32/51 (62.7%) and for IMRT/VMAT: 15/23 (65.2%) p=0.83. The rate of pCR was similar: for 3DCRT 17/51 (33.3%) and for IMRT/VMAT 8/23 (34.8%) p=0.9. Percent of pathological residual disease (mean±SD) was for 3DCRT: 16 % (SD±25.5) and for IMRT/VMAT: 22% (SD±27.2) p=0.36. Margins were negative in 90.1% (46/51) of patients treated with 3D vs. 89.4% (17/19) in IMRT/VMAT p=1. At median follow-up of 3.2 years, 2 year local control of 83% (95%CI 70-91%), 2 yrs DFS was 59% (95%CI 46-70) and 3 yrs OS was 72.3% (95%CI 58-82). There was no difference

radiotherapy. All patients were treated with three- dimensional radiation therapy (3DRT). Radiotherapy was administered five times per week at 1.8-2.0 Gy per time, for a total dose of 60-66Gy. Consecutive eligible patients were assigned to cohorts of nine. SUVmax of each cohort was increased from 3.5 to 6.5, 9.5, 12.5, 15.5, and so on. The cut off value of V20 was 30%. Results There were 54 patients with V20 < 30% and 6 patients with V20 > 30%. There were no statistically significant differences in the different SUVmax cohortes between the non RP group and the RP group. Eighteen percent of all patients had lung toxicity grade 2. However, no one had severe toxicity. Among our patients there was no difference in the occurrence of lung toxicity either depending of the SUVmax or V20, or their interaction (p=1). Conclusion In conclusion, the FDG uptake in lung tissue prior irradiation was not associated with the V20 to predict radiation pneumonitis among our patients. EP-1336 Immunogenic prognostic factors in patients with brain metastases from non-small cell lung cancer H. Doi 1 , K. Nakamatsu 1 , S. Anami 1 , T. Uehara 1 , Y. Wada 1 , K. Fukuda 1 , M. Inada 1 , K. Ishikawa 1 , S. Kanamori 1 , H. Monzen 1 , Y. Nishimura 1 1 Kindai University Faculty of Medicine, Department of Radiation Oncology, Osaka-Sayama, Japan Purpose or Objective Immune checkpoint inhibitors have significantly improved survival outcomes among patients with recurrent and refractory non-small cell lung cancer (NSCLC). Whole brain radiotherapy (WBRT) might be useful for both intracranial tumor control and improving the immune response to systematic disease. This study aimed to identify prognostic factors for brain metastases (BMs) from NSCLC after WBRT. However, there are no clear prognostic factors for WBRT, especially among patients with BMs in terms of their potential immune response. Therefore, the present study aimed to identify prognostic factors for response to radiotherapy among patients with BMs from NSCLC. Material and Methods This study retrospectively evaluated 100 consecutivepatients who underwent WBRT for BMs from NSCLCbetween December 2012 and October 2017. All patients had pathologically confirmed NSCLC (82 adenocarcinoma, 12 squamous cell carcinoma, and 6 others) and a diagnosis of BMs using images. Blood test data from between 4 weeks before WBRT and the first day of the WBRT course were available. All patients were typically treated using conventional external beam radiotherapy with opposed lateral treatment fields that encompassed the entire brain. The prescribed dose was calculated at the isocenter of the radiation fields based on daily treatments. Patients received a median dose of 30 Gy (range; 14- 45 Gy) in 10 fractions (5- 18 fractions). Clinical factors were tested for associations with overall survival after WBRT. Results The median follow-up time was 134 days (range: 14–1,395 days), and the median survival time was 143 days, and the 1-year survival rate was 30.4%. Univariate analyses revealed that better survival was associated with an Eastern Cooperative Oncology Group performance status(ECOG-PS)of 0–1, adenocarcinoma pathology, programmed death-ligand 1 (PD-L1) expression, no history of local therapy for BMs, no extracranial disease, LDH levels of <1.5 times the upper limit of normal, a neutrophil-to-lymphocyte ratio (NLR) of <5.0 (11-13), an RPA class of ≤2, and a GPA score of ≥1.5. In the multivariate analyses, better survival was independently associated with PD-L1 expression, no history of local