ESTRO 38 Abstract book

S734 ESTRO 38

(p<0.0001), LDH levels in the normal range (p=0.0036), RTOG-RPA class 2 (p=0.0013), and a GPA score of ≥1.5 (p=0.0486). In patients with normal and elevated LDH values, the 1-year survival rate was 54.7% and 17.6%, respectively. No significant impact on survival after WBRT was observed for the clinical stage at the initial diagnosis, presence of BMs at the initial diagnosis, maximum diameter of BMs, number of BMs, prescription dose of WBRT (Gy), or the pre-WBRT serum levels of NLR and PLR. In multivariate analyses, elevated LDH levels (p=0.0133) and presence of symptoms due to BMs (p=0.0130) were found as significant independent predictors of poor survival. Conclusion The present study revealed that high LDH level and the existence of BM-related symptoms predict a significantly poor survival after WBRT for BMs from SCLC. Elevated LDH may yield valuable information to identify patients with BMs who have poor survival outcomes. EP-1341 Evaluation of tumor motion variability with and without abdominal compression plate in lung SBRT K. Talapatra 1 , V. Raturi 1 , R. Vadgaonkar 1 , S. Jadhav 1 , P. Chadha 1 , V. Mhatre 1 , S. Pilakkal 1 1 Kokilaben Dhirubhai Ambani Hospital and Medical Research Institute, Radiation Oncology -, Mumbai, India Purpose or Objective To evaluate the significance of abdominal compression plate (ACP) with respect to variability in lung tumor motion and setup. Material and Methods Fifteen consecutive lung cancer patients who received SBRT in our institute between January 2016 and December 2016 were enrolled prospectively. All patients were immobilized using Vacloc on SBRT base plate. Out of fifteen, six patients were treated with ACP and remaining nine were treated without plate. Cone beam CT scan was acquired before delivery of each fraction and appropriate shifts were applied after matching target volumes and OARs. Mean and standard deviation were calculated. Unpaired t test used for statistical analysis and all values p<0.05 was considered as statistically significant. Results Tumor was located in upper lobe for 10 patients, in middle lobe for 2 and in lower lobe for 3 patients. Mean tumor motion was observed without ACP in comparison to with ACP is cranio-caudal (CC) direction 0.36±0.2cm versus 0.37± 0.15 cm( p=0.28, CI: 0.32 to 0.1), in antero-posterior (AP) direction 0.34±0.2 cm versus 0.37±0.15 cm (p=0.879, CI: 0.19 to 0.22), in medio-lateral (ML) 0.38±0.14 cm versus 0.26 ±0.09 cm (p=0.1, CI: 0.25 to 0.02) and rotation motion observed was pitch 0.77 0 ±0.46 0 versus 0.37 0 ± 0.1 0 (p=0.06, CI: 0.82 to 0.02), roll 1.24 0 ±0.8 0 versus 0.36 0 ±0.21 0 (p=0.02, CI: 1.6 to 0.14), yaw 0.04 0 ±0.43 0 versus 0.28 0 ±0.18 0 (p=0.001, CI: 1.17 to 0.36).

Results 101 patients and 143 lesions with median follow up time of 24 months were included for the analysis. 22 patients with 22 lesions were early NSCLC and 79 patients with 121 lesions were lung metastases in which 40% were from colorectal cancers and 21.4% were from primary lung cancers. SBRT fractionation ranged from 48-60 Gy in 3-5 fractions (10-18 Gy/fraction, BED 100-151 Gy10) and 25- 60 Gy in 1-7 fractions (5-25 Gy/fraction, BED 36-180 Gy10) for early NSCLC and oligometastatic lung cancers, respectively. All patients completed treatment without any interruption. Mean tumor volume was 22.7 cc and mean PTV volume was 52.1 cc. 2-year LC, PFS and OS were 90.9%, 50.3% and 83.5% for early NSCLC, and 92.6%, 50% and 74.8% for metastatic lung cancers. Early toxicity was low with only five percent reporting CTCAE grade 2. The most common acute toxicity was pneumonitis (23.7%). No toxicity greater than grade 2 was found for early and late toxicity. BED>70 Gy10 was associated with better OS compared with less than 70 Gy for lung metastasis (HR 0.29, 95%CI = 0.09-0.84). Conclusion Lung SBRT using FFF-technique provides promising clinical outcomes for both early-stage NSCLC and oligometastatic lung cancer patients. BED>70Gy10 in metastatic lung cancers may be adequate to yield good LC and OS. A prospective study is encouraged to confirm this result. EP-1340 Lactate dehydrogenase predicts survival in small cell lung cancer patients with brain metastases S. AnamI 1 , H. Doi 1 , K. Nakamatsu 1 , T. Uehara 1 , Y. Wada 1 , K. Fukuda 1 , M. Inada 1 , K. Ishikawa 1 , S. Kanamori 1 , Y. Nishimura 1 1 Kindai University Faculty of Medicine, Department of Radiation Oncology, Osaka-Sayama, Japan Purpose or Objective Small-cell lung cancer (SCLC) represents < 20% of total lung cancer cases with poor survival outcome especially in patients with extensive disease. SCLC patients often develop brain metastases (BMs) over the course of the disease. However, specific predictors for outcomes associated with SCLC and BMs remain unclear. Material and Methods Between February 2008 and December 2017, we identified 48 consecutive patients with BMs from SCLC who underwent WBRT at our institution. All patients had pathologically confirmed SCLC with a diagnosis of BMs, which was based on images.Blood test data between 4 weeks before the WBRT and the first day of WBRT treatment were available. When WBRT started, all patients had extracranial diseases except for one.The median age was 70 years; 42 (88%) and 6 (13%) patients were male and female, respectively. At the initial staging, 32 (67%) and 16 (33%) patients had extensive disease (ED) and limited disease (LD) SCLC, respectively. In addition, 22 (46%) patients had BMs at the time of the initial diagnosis of SCLC. All patients were typically treated with WBRT using conventional external beam radiotherapy and lateral-opposed treatment fields that encompassed the entire brain. Thirty-three (69%), 6 (13%), and 9 (19%) patients received the prescribed total dose of 30 Gy in 10 fractions, 37.5 Gy in 15 fractions, and 40 Gy in 16 fractions, respectively. Results Forty patients died in the follow-up period. Symptoms due to BMs were observed in 25 (52%) patients. Among the 25 patients with symptomatic BMs, 16 (64%) showed symptom improvement after WBRT. The median survival was 232 days and the 1- and 2-year overall survival rates were 34.4% and 5.8%, respectively. The intracranial failures were found in 36% of patients.Univariate analyses revealed that longer survival was associated with 5 factors: Eastern Cooperative Oncology Group performance status (ECOG-PS) of 0–1 (p=0.0006), asymptomatic BMs

Conclusion This study demonstrates the benefit of the abdominal compression plate in respiratory tumor motion to produce a high efficient decrease in breathing induced tumor motion especially the rotational movements ( roll and yaw ).