Comparison of Twice-Daily Radiation Therapy to 54 Gy by Simultaneous Integrated Boosting Technique and Once-Daily Radiation Therapy to 60 Gy for Limited Stage Small Cell Lung Cancer

E508

International Journal of Radiation Oncology  Biology  Physics

None. S.B. Lim: None. M. Chawla: None. R.P. Lee: None. A. Rimner: Research Grant; Boehringer Ingelheim, Pfizer, Varian Medical Systems. Advisory Board; Astra Zeneca, Pfizer. Travel Expenses; Varian Medical Systems.

received prophylactic cranial irradiation (PCI). We initiated this study to exploit risk factors for BM after PCI and develop harzard model to guide the clinical practice in LD-SCLC. Materials/Methods: LD-SCLC patients with PCI history from two institutions during 2003 and 2014 were retrospectively reviewed. BM free survival (BMFS), disease-free survival (DFS), extracranial disease-free survival (ECDFS), local recurrence-free survival (LRFS), and overall survival (OS) were estimated using Kaplan-Meier method. High risks and harzard model for BM were identified using univariate and multivariate Cox regression analyses. Results: A total of 257 patients were eligible, among whom 47(18.3%) experienced BM at median follow-up of 34 months. In univariate analyses, performance status (PS) and thoracic radiotherapy schedule were associated with BM(P < 0.05). Multivariate analyses showed that worse PS (PS > 1),thoracic hyperfractionated accelerated radiotherapy (HART), longer start of any therapy to the end of radiotherapy(SER) were independent risks for BM and surgery was independent protective factor for BM (P < 0.05). Median LRFS, ECDFS, DFS and OS in the BM group were much shorter than the non-BM group(P < 0.05).In addition, elder than 60-yr, worse PS and PCI classification were independent risk factors for OS(P < 0.05). Surgery and thoracic radiotherapy biological effective dose (TRTBED) were independent protective factors for OS (P < 0.05). Conclusion: Worse PS, thoracic HART and longer SER were independent risks for BM after PCI in SCLC. Surgery decreased BM rate and improve OS. Prognosis was much worse in the BM group. Higher dose for PCI did not prolong BMFS but shortened OS. Further studies are needed to confirm our findings. Author Disclosure: H. Zeng: None. R. Li: None. S. Yuan: None. P. Xie: None. X. Sun: None. X. Meng: None. B. Fan: None. W. Li: None. J. Yu: None.

3203 Comparison of Twice-Daily Radiation Therapy to 54 Gy by Simultaneous Integrated Boosting Technique and Once-Daily Radiation Therapy to 60 Gy for Limited Stage Small Cell Lung Cancer J. You,1 A. SHI,1 L. Jiang,1 D. Yang,1 H. Yu,1 R. Yu,1 and G. Zhu2; 1Key laboratory of Carcinogenesis and Translational Research (Ministry of Education/Beijing), Department of Radiation Oncology, Peking University Cancer Hospital & Institute, Beijing 100142, P.R. China, Beijing, China, 2 Department of Radiaton Oncology, China-Japan Friendship Hospital, Beijing, China Purpose/Objective(s): The aim was to compare twice-daily radiotherapy by simultaneous integrated boosting (SIB) technique with once-daily radiotherapy for patients of limited-stage small cell lung cancer (LSSCLC). Materials/Methods: Consecutive patients with LS-SCLC treated with definitive concurrent chemotherapy with twice-daily radiotherapy schedules by SIB technique or once-daily radiotherapy schedules were reviewed. In the twice-daily radiotherapy (BID) group, gross tumor volume (GTV) was 54Gy in 30 fractions (1.8Gy per fraction twice a day). In the oncedaily radiotherapy (QD) group, GTV was 60Gy in 30 fractions (2.0Gy per fraction once a day). Prophylactic cranial radiation (25Gy in 10 fractions) was administered to patients achieving complete response or partial response. The primary endpoints were 1-year overall survival (OS), progression-free survival (PFS) and local regional recurrence free survival (LRRFS). The secondary endpoint was treatment-related toxicity. Results: Between March 2015 and May 2016, 50 patients with LS-SCLC undergoing concurrent chemo-radiotherapy were included (20 patients in the BID group and 30 patients in the QD group). After a median follow-up for the radiotherapy comparison until data collection of 10.5 (4.2-19.7) months, the median PFS in the BID group was not achieved, while the median PFS in the QD group was 8.6 (6.6-10.6) months. The 1-year OS rates in the BID group and QD group were 86.0% vs 78.0% (PZ0.724), respectively. The PFS rate at 1-year was estimated at 68.0% in the BID group, compared with 43.0% in the QD group (PZ0.336). The LRRFS rates at 1 year were 87.0% in the BID group and 77.0% in the QD group (PZ0.370). There was a trend towards improved survival in the BID group. No statistically significant difference was found in the treatmentrelated toxicities between the two groups. Conclusion: Twice-daily radiotherapy with SIB technique to 54Gy had a superior tendency in survival compared with once-daily radiotherapy to 60Gy for LS-SCLC without adding toxicity. A further randomized study of comparing twice-daily radiotherapy by SIB technique with once-daily radiotherapy for LS-SCLC is required. Author Disclosure: J. You: None. A. SHI: None. L. Jiang: None. D. Yang: None. H. Yu: None. R. Yu: None. G. Zhu: None.

3204 Hazard Model for Brain Metastases After Prophylactic Cranial Irradiation in Local Disease Small Cell Lung Cancer H. Zeng,1,2 R. Li,3 S. Yuan,2 P. Xie,2 X. Sun,2 X. Meng,2 B. Fan,2 W. Li,2 and J. Yu2; 1School of Medicine and Life Sciences, University of JinanShandong Academy of Medical Sciences, Jinan, Shandong 250022, China, Jinan, China, 2Department of Radiation Oncology, Shandong Cancer Hospital Affiliated to Shandong University, Jinan, China, 3Department of Radiation Oncology, Sichuan Cancer Hospital, Chengdu, 610041, China, Chengdu, China Purpose/Objective(s): Some patients with local-disease small cell lung cancer (LD-SCLC) still experience brain metastases (BM) even have

3205 Factors Associated With Survival in Patients With Nonesmall Cell Lung Cancer from a Single Institution Study of 3569 Patients H. Zhang,1 W. Wang,2 G. Durm,3 K. Kesler,4 and F.M. Kong2; 1 Department of Radiation Oncology, Indiana University, Indianapolis, IN, 2 Department of Radiation Oncology, Simon Cancer Center, Indiana University School of Medicine, Indianapolis, IN, 3Department of Medicine, Indiana University, Indianapolis, IN, 4Department of Surgery, Indiana University, Indianapolis, IN Purpose/Objective(s): Non-small cell lung cancer (NSCLC) constitutes more than one quarter of cancer deaths in the United States. The primary aim of this study is to identify risk factors and build a model for overall survival prediction based on patient and tumor factors from a large single institution database. Materials/Methods: The study population was taken from our cancer registry of 8620 lung cancer patients treated in the Indiana University Health System between 2000 and 2016. Patient and tumor factors were tested for their correlation with survival. The patient records with loss to follow up were censored. The survival analysis was performed using a multivariable cox proportional hazards regression model with R. The accuracy of the models were assessed by 8 folder cross validation. Results: After excluding other histologies and duplicate registered cases, 3569 patients with confirmed NSCLC and complete staging data were eligible for this analysis. Median follow-up was 16.7 months in all patients and 41.8 months for alive patients. The median/5-year OS were 34.3 months/51.3%, 27.1 months/44.0% (HR Z 1.2, p Z 0.03), 14.2 months/ 18.0% (HR Z 2.4, p Z 2e-16) and 6.3 months/6.7% (HR Z 4.9, p Z 2e16) for stage I, II, III and IV, respectively. Age, gender, race, marital status, smoking status, tumor size, stage, year of diagnosis and treating hospital were significant factors for survival (all p<0.001). Using these significant factors, a multivariate cox proportional hazard regression model was built, with the stage adjusted by gender (HR Z 0.8 for female, p Z 9.52e-7), smoking status (HR Z 1.2 for current smoker, p Z 0.001), age (HR Z 1.03, p Z 2e-16), marital status (HR Z 1.2 for single, p Z 0.001), tumor