ESTRO 38 Abstract book

S757 ESTRO 38

Results From Apr, 2010 to May, 2015, 77 patients were included in this study. Forty-two patients received WBI dose more than 21 Gy, and the other 35 received ≦ 21 Gy. In the GPA class 0-1, the median survival of HWBI group (n=21) was longer than the LWBI group (n=13) (2.26 vs. 1.03 months, p=0.075). In the GPA class 1.5-2.5, the median survival of HWBI group (n=20) was shorter than the LWBI group (n=20) (23.13 vs. 29.37 months, p=0.09). Conclusion With the potential of better neurocognitive function preservation, WBI dose ≦ 21 Gy showed a survival outcome non-inferior to 30 Gy. Although no significant difference detected, there is a trend encouraging to apply lower WBI dose to patients with higher GPA scores (1.5-2.5) for better survival benefit. Further prospective trials are required to confirm the optimal brain radiotherapy regimen for NSCLC patients with brain metastases. EP-1390 Association between heart dose and survival for NSCLC patients underwent VMAT C. XIE 1 , X. Jin 1 1 the 1st Affiliated Hospital of Wenzhou Medical Univiersity, Radiation and Medical Oncology, Wenzhou, China Purpose or Objective One critical finding of RTOG 0617 was that heart dose could impact the early overall survival (OS) of non-small cell lung cancer (NSCLC) patients underwent radiotherapy (RT), although mixed results were reported in studies trying to confirm this finding, studies all suggested that heart dose should be minimized during radiotherapy planning based on the known adverse effects of RT on vasculature and cardiac function. Intensity-modulated radiotherapy (IMRT) had been demonstrated to decrease the dose to lung and heart compared with 3D conformal radiotherapy. As an extended form of IMRT, volumetric modulated arc therapy (VMAT) is able to achieve similar dosimetric distribution while decreasing MU and treatment delivery time compared with IMRT. The purpose of this study is to investigate the efficacy and safety of VMAT, as well as the association of lung and heart dosimetry with OS in the NSCLC patients treated by VMAT. Material and Methods 200 consecutive inoperable NSCLC patients treated by VMAT from March 2011 to September 2016 were retrospectively reviewed. OS rates were estimated with the Kaplan-Meier method. The Cox regression model estimated the hazard ratio (HR) and the corresponding 95% confidence interval (CI) for univariate (UVA) and multivariate (MVA) analyses. Multivariate model building was performed using stepwise regression (modification of the forward selection method) techniques utilizing significant univariate factors to avoid over-fitting the There were 174 NSCLC patients enrolled in this study with a median age of 63 years (range from 34-86 y). The average OS for these patients were 25.02 months with a median followup of 14.77 months. For an average prescribed dose of 55.90±0.50 Gy, the mean dose, V25, V30 and V 50 to heart were 16.03±0.63, 28.73%±1.51%,25.80%±1.42%, and 8.38%±0.86%, and the mean dose, V5,V10,V13,V20 and V30 to lung were 13.78±0.31 Gy,55.07%±1.54%,40.68%±1.30%,33.2%±1.09%,23.03%±0.6 7%,and 15.22%±0.42%, respectively. Univariate analysis indicated that V30 of heart was associated with overall OS with a p value of 0.044, no other heart and lung dosimetric parameters was associated with OS. The V13 of lung was associated with acute radiation pneumonia with an RP rate of 9.78%.The dosimetric values of heart and lung were strongly correlated with each other. Conclusion model. Results

treatment planning considerations, clinical outcomes, and toxicity ratesof SABR following pneumonectomy. Material and Methods A systematic review of the literature was conducted in accordance with PRISMA guidelines using PubMed and EMBASE from inception to July 2018. A total of 220 entries were identified. Articles were limited to those published in the English language. 114 unique articles were assessed for eligibility. Inclusion criteria consisted of non-review articles involving at least 2 patients who received lung SABR post-pneumonectomy. Two reviewers independently performed abstract and full-text review, with discrepancies settled by a third reviewer. Results Of the 114 articles identified by the initial search, 10 articles comprising 108 patients who received lung SABR post-pneumonectomy met inclusion criteria. Median age was 70.8 (range 58.0-75.5), and most patients were male (median 77.0%, 73.9-100%, n=5). The weighted average incidence of grade 3 or higher toxicity was 11.7% (0-33.3%, n=9). There were 2 treatment-related deaths from one case series. Another death was reported that was infectious in nature, but the attributable effects of radiation could not be ruled out. The median 1-year rate of logoregional control was 90.2% (range 84.0-100%, n=6), which is consistent with previously published SABR data. Median BED 10 was 107.9 Gy (87.5-151.2 Gy, n=8), and the most common dose fractionation schemes were 54 Gy in 3 fractions (n=7), 48 Gy in 4 fractions (n=6), and 50 Gy in 5 fractions (n=5). The majority of studies used 4DCT image acquisition (9/10), a technique that captures a 3DCT volume over a period of time thereby describing the motion of a desired target. Respiratory gating was only employed in a single study. Conclusion SABR appears to be a safe and effective option for solitary pulmonary nodules in survivors of lung cancer with prior pneumonectomy. Multi-institutional and/or prospective studies would be helpful to determine the true risk and appropriateness of SABR in this high-risk patient population. EP-1389 Lowered Whole Brain Irradiation Dose for Non-Small Cell Lung Cancer Patients with Brain Metastases Y. Wang 1 1 Taipei Tzu Chi Hospital, Radiation Oncology, New Taipei City, Taiwan Purpose or Objective Non-small cell lung cancer (NSCLC) patients with brain metastases are traditionally treated with 30 Gy of whole brain irradiation (WBI). However, it has been reported to be correlated with neurocognitive function decline. In this study, we analyzed the survival of patients treated with different WBI dose to evaluate if lowered WBI dose provides comparable treatment outcome. Material and Methods We reviewed stage IV NSCLC patients with brain metastases who underwent brain irradiation at our hospital with the following exclusion criteria: 1) previous brain irradiation history; 2) brain metastases resected before irradiation; 3) poor medical condition with early termination of radiotherapy. The radiotherapy regimen for brain metastases varied from WBI only, WBI followed by metastatic tumor boost, to boost alone without WBI. The Graded Prognostic Assessment (GPA) score was calculated for each patient by their age, Karnofsky performance scores, number of cranial metastases, and if extracranial metastases were present. The survival time was calculated from the day radiotherapy completed. Kaplan-Meier survival analyses were performed separately for patients received WBI dose > 21 Gy (HWBI group) or ≦ 21 Gy (LWBI group) in each GPA class, and the difference between the groups was tested with the log-rank test.