ESTRO 36 Abstract Book

S263 ESTRO 36 2017 _______________________________________________________________________________________________

difference in overall survival (OS), Quality of Life or use of dexamethasone. These unexpected results were criticized because OS was poorer (2 months) than the alleged survival in common radiotherapy practice, suggesting selection bias. Indeed, only 6% of included patients had a favorable RPA class 1. Furthermore, patients with a more favorable primary tumor such as breast cancer, could perhaps benefit more from WBRT. Therefore, we compared the QUARTZ data with survival after WBRT in ‘common radiotherapy practice’ from a large multicenter retrospective cohort in the Netherlands. Material and Methods Survival data from all patients with brain metastases from NSCLC or any type of breast cancer treated with WBRT between 2000 and 2014 were analyzed. Patients were treated in seven different institutes (both academic and non-academic covering 33% of Dutch radiotherapy practices). All patients were treated with 5 fractions of 4 Gy. Survival was calculated from the first day of radiotherapy until the day of death or last follow-up. Date of death was retrieved from the Dutch Municipal Personal Records Database. Results Between 2000 and 2014, 3270 patients were identified, 2384 with brain metastases from NSCLC (73%) and 886 from primary breast cancer (27%). The median OS was 2.7 months for the NSCLC group and 3.8 months for the breast cancer group (p<0.001). At time of analysis, 97% of all patients was deceased. There was no difference between academic and non-academic centres. No correlation between the year of treatment and OS was found. Conclusion The survival of patients after WBRT for brain metastases from NSCLC treated in Dutch ‘common radiotherapy practice’ is practically the same as in patients treated in the British QUARTZ study. Survival for patients with brain metastases from breast cancer is only marginally better. Our analysis supports the conclusion from the QUARTZ study that there is insufficient evidence to consider WBRT the standard of care for patients with multiple brain metastases. We advocate more studies in this patient population and recommend a more restrictive use of WBRT in daily radiotherapy practice. PV-0505 Association between the diagnosis-to- treatment interval and overall survival in Taiwan OSCC C.T. Liao 1 , Y.W. Wen 2 , S.H. Ng 3 , L.Y. Lee 4 , C.Y. Lin 5 , H.M. Wang 6 , C.H. Lin 7 , T.C. Yen 8 1 Chang Gung Memorial Hospital, Otorhinolaryngology- Head and Neck Surgery, Taoyuan, Taiwan 2 Chang Gung University, Clinical Informatics and Medical Statistics Research Center, Taoyuan, Taiwan 3 Chang Gung Memorial Hospital, Diagnostic Radiology, Taoyuan, Taiwan 4 Chang Gung Memorial Hospital, Pathology, Taoyuan, Taiwan 5 Chang Gung Memorial Hospital, Radiation Oncology, Taoyuan, Taiwan 6 Chang Gung Memorial Hospital, Medical Oncology, Taoyuan, Taiwan 7 Chang Gung Memorial Hospital, Plastic and Reconstructive Surgery, Taoyuan, Taiwan 8 Chang Gung Memorial Hospital, Nuclear Medicine, Taoyuan, Taiwan Purpose or Objective To investigate the association between the diagnosis-to- treatment interval (DTI) and overall survival (OS) in patients with oral cavity squamous cell carcinoma (OSCC). Material and Methods A total of 18,677 patients with first primary OSCC identified in the Taiwanese Cancer Registry Database between 2004 and 2010 were examined. The effect of DTI on 5-year OS rates was investigated with multivariate Cox regression analysis. After the identification of the optimal

cutoff for DTI based on the 5-year OS rates, DTI was classified in the following 20-day groups: ≤20 days (57% of the study patients), 21−45 days (34%), 46−90 days (6%), and ≥91 days (3%). In additional exploratory analyses, DTI was reclassified in the following 30-day interval groups: ≤30 days (81% of the study patients), 31−60 days (14%), 61−90 days (2%), and ≥91 days (3%).

Results Multivariate analyses identified DTI (≤20 days vs. other subgroups), sex (female vs. male), age (<65 vs. ≥65 years), clinical stage (p-Stage I vs. p-Stage II, III, IV), and treatment modality (initial surgery vs. initial non-surgery) as independent prognostic factors for 5-year OS. Compared with a DTI ≤20 days, the DTI categories ≥91 days (hazard ratio [HR]: 1.28, P <0.001), 46−90 days (HR: 1.25, P <0.001), and 21−45 days (HR: 1.07, P =0.007) were independently associated with a higher risk of 5-year mortality. Similar results were obtained for DTI ≤30 days groups. Conclusion DTI is independently associated with 5-year OS in OSCC patients. A DTI longer than 30 days or even 20 days may potentially decrease survival. PV-0506 Comparison of Clinical Behavior of Viral Related Oropharyngeal and Nasopharyngeal Carcinoma S.H. Huang 1 , J. Waldron 2 , J. Su 3 , S. Bratman 2 , J. Kim 2 , A. Bayley 2 , J. Ringash 2 , M. Giuliani 2 , A. Hope 2 , J. Cho 2 , A. Hansen 4 , R. Jang 4 , J. De Almeida 5 , B. Perez-Ordonez 6 , I. Weinreb 6 , L. Tong 2 , W. Xu 3 , B. O'Sullivan 2 1 Princess Margaret Cancer Centre University Health Network, 2B-Radiation Therapy, Toronto, Canada 2 Princess Margaret Cancer Centre / University of Toronto, Radiation Oncology, Toronto, Canada 3 Princess Margaret Cancer Centre / University of Toronto, Biostatistics, Toronto, Canada 4 Princess Margaret Cancer Centre / University of Toronto, Division of Medical Oncology, Toronto, Canada 5 Princess Margaret Cancer Centre / University of Toronto, Otolaryngology - Head & Neck Surgery, Toronto, Canada 6 Princess Margaret Cancer Centre / University of Toronto, Pathology, Toronto, Canada Purpose or Objective To compare clinical behavior between viral related oropharyngeal (OPC) and nasopharyngeal carcinoma (NPC) We reviewed all newly diagnosed viral related OPC and NPC treated with IMRT from 2005-2014. Viral etiology was confirmed by p16 immunohistochemistry staining for HPV and EBER in situ hybridization for EBV. Demographics, the new HPV+ OPC specific UICC/AJCC TNM (ICON-S) and at a western institution. Material and Methods