ESTRO 36 Abstract Book

S579 ESTRO 36 2017 _______________________________________________________________________________________________

The BTV ATA (17 vs. 15 cc) but the difference was not statistically different (p> 0.05), the CI was 0.8 and the DICE was 0.2. Table 1. Tumour Volumes defined by the three different methods. GTV Mean Volume (cc) Ranges Standard Deviation GTV ST 21.4 4.5 – 66.3 ±16.0 GTV 40%SUV 14.7 1.3 – 58.5 ±13.7 GTV T ATA 17.2 1.5 – 61.5 ± 12.8 Conclusion The proposed adaptive thresholding algorithm resulted robust and reproducible in the clinical context of head and neck tumours. The tumour volumes obtained by the algorithm were a part of the GTV ST and were similar to GTV 40%SUV. This tumour volume could allow the delineation of a BTV for dose escalation in head and neck cancer treated with IMRT-SIB. EP-1060 Analysis of failure patterns and prognostic factors after postoperative IMRT for buccal cancer Y.W. Lin 1 , L.C. Lin 1 1 Chi Mei Medical Center, Department of Radiation Oncology, Tainan, Taiwan Purpose or Objective Squamous cell carcinoma (SCC) of buccal mucosa has a high incidence of locoregional failure. Its aggressive behavior and the change of lymphatic and vascular drainage after surgery make the design of radiotherapy difficult. The aim of this study is to analyze failure patterns and prognostic factors in patients with locally advanced buccal cancer after postoperative intensity modulated radiotherapy (IMRT). Material and Methods Between January 2007 to October 2012, 84 patients with histological confirmed SCC of buccal mucosa underwent surgery followed by postoperative IMRT were retrospectively analyzed.. All patients were stage III/IV buccal cancer. The high-risk clinical target volume (CTV) covered the surgical tumor bed and ipsilateral or bilateral upper neck. The median dose to high-risk CTV was 60Gy. Analyzed end-points were overall survival (OS), local recurrence-free survival, loco-regional recurrence-free survival, supra-mandibular notch recurrence-free survival, distant metastasis-free survival, prognostic factors and patterns of failure. Results The median follow up was 51 months (range, 2-112 months). The first recurrent sites were local tumor bed (17 patients) with or without regional/distant recurrence. The median time from treatment completion to first locoregional recurrence was 7.3 months. Of the 17 patients with local recurrence, 11 exhibited the supra- mandibular notch recurrence; most were classified as marginal failure. The estimated 4-year local failure-free, locoregional failure-free, distant metastasis-free and overall survival rates were 72%, 63.3%, 85.9% and 68.8%. In multivariate analysis, lymphovascular invasion (P = 0.002), N2 disease (P = 0.003), and ratio of tumor thickness to tumor size larger than 1/3 (P = 0.014) were independent prognostic factors for overall survival. Patients received tumor excision with maxillectomy was a predictive factor for the development of supra-mandibular notch recurrence. Conclusion SCC of buccal mucosa is a highly aggressive form of oral cavity cancer with a high locoregional failure rate and most locoregional recurrences led to lethal events. Design of postoperative IMRT for buccal cancer, especially CTV delineation, based on failure patterns and clinicopathological prognostic factors might transfer into was bigger than the GTV 40%SUV

better disease control.

EP-1061 Towards a validated Decision Aid Tool for advanced larynx cancer patients A.J. Berlanga 1 , M. Petersen 2 , F. Hoebers 1 , S. Delbressine 1 , M. Van den Breke 2,3,4 , P. Lambin 1 1 Maastro Clinic, GROW School for Oncology and Developmental Biology- Maastricht University Medical Centre, Maastricht, The Netherlands 2 The Netherlands Cancer Institute, Department of Head and Neck Surgery and Oncology, Amsterdam, The Netherlands 3 Academic Medical Center, Department of Oral and Maxillofacial Surgery, Amsterdam, The Netherlands 4 University of Amsterdam, Institute of Phonetic Sciences, Amsterdam, The Netherlands Purpose or Objective Advanced larynx cancer patients may be eligible for more than one treatment: laryngectomy, radiotherapy, chemoradiation, or combinations thereof. These treatments have a distinct impact on quality of life (e.g. disfigurement, speech, swallowing problems), and outcomes depending on TNM-classification. To empower these patients to participate in shared- decision making, we are creating a web-based Patient Decision Aid Tool (PDA, www.treatmentchoice.info). The goal is help patients to understand treatment options and support clinicians to gain perspective of patients’ preferences. Material and Methods The PDA was validated following the International Patient Decision Aid Standards (IPDAS). First, a prototype was created considering literature and input from an interdisciplinary group. A mixed-method (interview, 5- Likert questionnaire) was used to identify patients’ decisional needs, and to evaluate if the tool was clear and perceived as useful for shared-decision making. Clinicians (N=8) and patients (N= 12) from two hospitals were included. Results Patients and clinicians agreed on patient’s difficulty to recall spoken information and understand risk probabilities. They mentioned the need of information about treatment options, side effects, and effectiveness. Patients asked for information about procedures before and after treatment. Patients preferred information that is simple, visual, and in small chunks. Clinicians preferred information adapted to patient’s psychosocial level. Patients were positive about the PDA. All criteria (satisfaction, effectiveness, clarity, usability, usefulness, intention use) had a median (IQR) of 4 ('agree”). Patients asked for simpler terms, information on psychological effects and the 'no treatment option”. Considering these results, a new version was created (Fig.1). It is a visual tool, containing video interviews with clinicians and animations to explain the treatments. This version will be validated by clinicians and patients for comprehensibility and usability. Results will be considered to create a final version. Thereafter, we will evaluate its impact on shared decision-making in a multi-center setting.