ESTRO 36 Abstract Book

S582 ESTRO 36 2017 _______________________________________________________________________________________________

The logistic regression and the random forest model achieved similar performance in predicting xerostomia (AUC=0.71). The developed signature consisted of one dosimetric parameter and one imaging feature. For the prediction of dysphagia both models achieved only a moderate prediction accuracy (AUC=0.55). Conclusion For prediction of xerostomia, a signature was developed and showed a good performance. For dysphagia only moderately performing models could be obtained in this cohort. Based on our results, subgroups of patients at a high risk of xerostomia may be identified and offered treatment adaption. However, further investigations are currently ongoing, i.e., externally validating the developed signature, which is an important step in developing clinically relevant prediction models. EP-1066 Hypofractionated accelerated SIB-VMAT radiotherapy for H&N cancer: brachial plexus constraint M. Nuzzo 1 , L.P. De Vivo 1 , F. Deodato 1 , G. Macchia 1 , M. Ferro 1 , M. Ferro 1 , L.G. Serino 1 , S. Cilla 2 , S. Cammelli 3 , A. Farioli 4 , A. Arcelli 3,5 , A. Veraldi 3 , G.P. Frezza 5 , V. Valentini 6 , A.G. Morganti 3 1 Fondazione di ricerca e cura "Giovanni Paolo II", Radiotherapy Unit, Campobasso, Italy 2 Fondazione di ricerca e cura "Giovanni Paolo II", Medical Physics Unit, Campobasso, Italy 3 University of Bologna, Radiation Oncology Center- Department of Experimental- Diagnostic and Speciality Medicine - DIMES, Bologna, Italy 4 University of Bologna, Department of Medical and Surgical Sciences - DIMEC, Bologna, Italy 5 Ospedale Bellaria, Radiotherapy Department, Bologna, Italy 6 Policlinico Universitario "A. Gemelli"- Universtà Cattolica del Sacro Cuore, Department of Radiotherapy, Rome, Italy Purpose or Objective To perform a dosimetric evaluation of the brachial plexus (BP) dose in locally advanced H&N cancer patients undergoing moderate hypofractionated-accelerated chemoradiation performed by a SIB-VMAT technique. Material and Methods Patients with locally advanced H&N cancer receiving induction chemotherapy (ICT) and subsequent platinum based concurrent radiotherapy were included in this retrospective analysis. Toxicity and outcomes data were recorded during the routine follow-up. In all patients, right (RBP) and left (LBP) BP were delineated according to RTOG guidelines by the same radiation oncologist. RBP and LBP mean doses, V50, V55 and V60 were recorded and correlated with late neurological toxicity. Results From July 2010 to January 2015, 50 patients [M/F: 40/10; median age: 57y, range 30-77; stage III: 11 (22%), stage IV: 39 (78%)] were treated and represent the object of the analysis. ORL subsites were as follows: oropharynx (22; 44%), epipharynx (8;16%), oral cavity (9; 18%), larynx (4; 8%) and hypopharinx (7; 14%). Cisplatin plus 5-fluorouracil chemotherapy schedule was administered as ICT in 72% of cases, while 22% of patients received a 3-drugs protocol (cisplatin, 5-fluorouracil and docetaxel). A moderate accelerated hypofractionation was delivered by using a 2 arc SIB-VMAT technique. Doses to macroscopic disease (T and N) ranged from 67.5/2.25 Gy (8 patients; 16%) to 70.5/2.35 Gy (42 patients; 84%), while the high and low risk nodal areas received 60/2 Gy/die and 55.5/1.85 Gy in 30 fractions, respectively. As per DVH analysis, LBP and RBP mean dose were 48.4 Gy and 48 Gy, V50 were 68.5% and 68.9%, V55 were 56.1%and 58.9%, V60 were 28% and 32.6%, respectively. In 44% of cases part of the LBP was included within the high dose PTV (67.5Gy in 12% and 70.5 Gy in 32% of patients). Conversely, in 46% of cases part of

the RBP was included within the high dose PTV (67.5Gy in 8% and 70.5 Gy in 38% of patients). With a median follow- up of 19 months (range 3-53) no symptoms of brachial plexopathy were reported, although in 87% of cases doses to BP exceeded the suggested literature constraint of 60 Gy. Conclusion A SIB-VMAT moderate accelerated hypofractionation at the doses reported in this analysis seems to be tolerable and safe, without cases of neurological toxicity. Longer follow-up and further prospective studies in larger series are warranted to confirm these findings. EP-1067 is adenoid cystic carcinoma (ACC) radioresistant?: the effect of radiotherapy for ACC of head and; neck I. Jung 1 , J. Kim 1 , S. Ahn 1 , S. Song 1 , S. Yoon 1 , S. Kim 1 , J. Park 1 , E. Choi 1 , S. Lee 1 1 Asan Medical Center- Univ of Ulsan, Radiation oncology, Seoul, Korea Republic of Purpose or Objective The adenoid cystic carcinoma (ACC) of head and neck showed insidious onset and usually advanced at initial presentation. Because of limitation of anatomy of head and neck, in some cases, wide excision may not be possible. And even further, in other cases surgical excision may not be possible. Therefore we evaluated efficacy and safety of definitive radiation therapy in head and neck ACC. Also, we analyzed prognostic factors in adjuvant radiation therapy of it. Material and Methods From January 1995 to December 2013, 94 patients received radiotherapy for head and neck adenoid cystic carcinoma in Asan medical center. Fourteen patients were excluded because of systemic metastasis (n=7), other primary cancer (n=3), incomplete RT (n=2), and previous RT history (n=2). We retrospectively reviewed records of 80 patients about clinical stage, pathologic characteristics, performing surgery or chemotherapy, aim of radiotherapy, radiation dose and technique, and clinical outcomes such as local recurrence, overall survival according to radiation groups. We analyzed prognostic factors of adjuvant RT such as stage, extent of surgery, resection margin, radiation dose, and chemotherapy. We also reviewed treatment related complication using CTCAE criteria version 4.0. All analyses were performed using SPSS, version 22. Results Median age at diagnosis was 51 years (21-82 years). Most common sites were salivary glands (n=35, 43.8%), oral cavity (n=14, 17.5%), and paranasal sinuses (n=12, 15.0%). Half of patients (n=41, 51.3%) had a locally advanced tumor at diagnosis (T3 : n=11, 13.8%), T4 : n=30, 37.5%). Sixty-nine patients underwent surgery. Detailed patient's characteristics according to RT aim were in table. Sixty- nine (86.2%) patients underwent adjuvant radiotherapy and 11 patients (13.8%) underwent definitive radiotherapy. Radiation dose were 50.4 – 76 Gy per 24-42 fx (median 64.8 Gy). With median follow-up of 114.3 months (9.7 – 236.3 months), local tumor progression was found in 21 patients (26.3%). 5 year overall surviva (OS)l rate was 82.4-91.4% in adjuvant arm and 72.7% in definitive arm. 5 year local recurrence free survival (LRFS) rate was 74.1-97.1 % in adjuvant arm, and 48.5% in definitive arm. Survival curves following treatment arms and stage were in graph. All patients tolerated the radiotherapy well. Conclusion Adjuvant radiotherapy to head and neck ACC seemed better clinical outcomes compared with definitive radiotherapy. However, in this report, all patients who received definitive radiation therapy were advanced stage (stage III :1, stage IV :10). Considering stage, 72.7% of 5YOS rate and 48.5% of 5YLRFS rate in definitive