ESTRO 36 Abstract Book

S575 ESTRO 36 2017 _______________________________________________________________________________________________

metastasis. Kaplan-Meier survival analysis revealed TLG (> vs. < 520), MTV (> vs. < 70), SUVmax (> vs. < 14.0) of primary tumor, and chemotherapy duration affected overall survival significantly (P=0.0004, P=0.0059, P=0.0209, and P=0.0039, respectively). Only TLG (P=0.0102) and MTV (P=0.0164) were significant factors for locoregional failure-free survival. In univariate analysis, chemotherapy duration (P=0.0101), SUVmax of the primary tumor (P=0.0279), MTV (P=0.0094), and TLG (P=0.0011) were significant predictors for death; MTV (P=0.0236) and TLG (P=0.0159) were significant factors in predicting locoregional recurrence. In multivariate analysis, both TLG and MTV revealed as an independent predictor for death (P=0.0057 and P=0.0156) and locoregional recurrence (P=0.0157 and P=0.0225). nguage:EN-US; total lesion glycolysis [TLG]). Conclusion TLG and MTV were the most important prognostic factors in predicting mortality and locoregional recurrence in patients with advanced SCCHN treated by IndCT followed by surgery/radiotherapy. EP-1051 Characteristics and Impact of HPV to Head and Neck Squamous Cell Carcinoma in Thai Patients C. Jiarpinitnun 1 , P. Pattaranutaporn 1 , N. Larbcharoensub 2 , T. Chureemas 3 , J. Juengsamarn 3 , N. Trachu 4 , S. Lukerak 3 , P. Chansriwong 3 , N. Ngamphaiboon 3 1 Ramathibodi Hospital, Radiology, Bangkok, Thailand 2 Ramathibodi Hospital, Pathology, Bangkok, Thailand 3 Ramathibodi Hospital, Medicine, Bangkok, Thailand 4 Ramathibodi Hospital, Research center, Bangkok, Thailand Purpose or Objective Head and Neck Squamous Cell Carcinomas (HNSCC) is the one of common malignancies in Asia. Smoking, alcohol consumption and betal nut chewing are well-known major risk factors. Association between human papilloma virus (HPV) and HNSCC, especially oropharyngeal sites, have been reported. However, most data reported were from the Western countries. This study evaluated the prevalence, the characteristics and the impact of HPV on the clinical outcomes of treatment in Thai HNSCC patient Material and Methods Non-nasopharyngeal HNSCC patients treated at our hospital between 2007 and 2013 were identified through the cancer registry database. Basel ine patient characteristics, treatment data and survivals were retrospectively reviewed. The formalin-fixed paraffin- embedded tissue sections were retrieved for p16 analysis. The HPV status was determined by p16 immunohistochemistry, defined by tumor cells demonstrated nuclear and cytoplasmic staining ≥70%. To identify the impact of HPV as prognostic factor, the survival outcomes were analyzed in cases which p16 status were confirmed. Results Total of 205 available FFPE tissues of HNSCC patients was evaluated for p16 expression. The p16 status was positive in 24 of 205 cases (11.7%); the positive p16 were found in men more than women with calculated ratio of 4:1 (20:4 cases). The oropharynx was the most common site found in p16 positive (34.4%), followed by larynx (11.4%), hypopharynx (11.1%) and oral cavity (3.2%). The p16 positive was shown in patients who were ever smokers (77.3%) more than non-smokers (22.7%). Clinical AJCC stage III-IV was presented in 17 (70.8%) of 24 HNSCC patients with p16 positive. Baseline patient characteristics and treatment characteristics were not statistically different between p16 positive and negative groups except the site of primary tumor (p<0.001). The 3- year overall survival was not statistically different but trended toward p16 positive group (62% vs. 41%, p=0.09). However, p16 positive HNSCC was significant superior in 3-year disease-free survival (3-yrs DFS 93% vs. 57%,

p=0.01) and in 3-year locoregional free survival (3-yrs LRFS 100% vs. 54%, p=0.007) when compared with p16 negative HNSCC patients. Conclusion In our study, the prevalence of HPV-related HNSCC in Thai patients was found to be less and the difference in some characteristics were observed when compared to the results reported from the Western countries. Nevertheless, DFS and LRFS were better in p16 status positive. The trend toward improved overall survival was also seen. The analyses suggested that p16 status is still a strong prognostic marker for HNSCC patient in Thailand. EP-1052 Hypofractionated vs. conventional radiotherapy for early glottic cancer: a propensity score analysis W. Takahashi 1 , H. Yamashita 1 , M. Sakuramachi 1 , T. Purpose or Objective The purpose of this study was to compare the treatment results and toxicity of hypofractionated radiotherapy (HRT) with conventionally fractionated radiotherapy (CRT) for early stage glottic squamous cell carcinoma (ESGC). Material and Methods A single-institutional retrospective study was conducted to review ESGC patterns of care and treatment outcome. From February 1998 to January 2016, 204 consecutive patients with T1-2N0 GSCC were treated in our institution. Forty-seven patients received HRT and 157 CRT. Using 4 MV photon beam, a median dose of 66 Gy (range, 60–70 Gy) was delivered with daily doses of 2.0 Gy/fraction (CRT) or 2.4Gy/fraction (HRT). None of the patients received prophylactic nodal RT. Patients in both treatment groups were matched using the propensity score matching method (1:2 ratio). Treatment outcome was analyzed in terms of local control rate (LCR), distant failure-free survival (DFFS), progression-free survival (PFS), overall survival (OS), and treatment-related adverse events (AE). Results The matched cohort consisted of 47 HRT and 94 CRT patients with the median follow-up of 27 and 62 months, respectively. Significant higher 5-year LCR and PFS were observed in the HRT group (96% vs. 82% and 96% vs. 76%, p=0.031 and 0.015, respectively). No significant differences in DFFS and OS were observed between groups. Most acute AE included grade 1-2 mucositis, dermatitis, dysphagia and/or hoarseness. Except for one patient who had grade 3 dysphagia in the CRT group, there was no grade 3 or greater chronic AE. Imae 1 , K. Okuma 1 , K. Nawa 1 , K. Nakagawa 1 1 University of Tokyo, Radiology, Tokyo, Japan

Conclusion This large, single-institutional experience of definitive radiotherapy for ESGC using HRT vs. CRT demonstrates that HRT achieved high rates of LCR and PFS with minimal long-term toxicity. Although these results must be