6th ICHNO Abstract Book

6th ICHNO 6 th ICHNO Conference International Conference on innovative approaches in Head and Neck Oncology 16 – 18 March 2017 Barcelona, Spain __________________________________________________________________________________________ page 39

Conclusion Adjuvant radio- or radiochemotherapy using IMRT with an EUD based prescription is safe. Recurrences occur mainly in or close to the tumor bed. PO-082 Correlation between HI, GI, CI and Size of Metastases for Linac-Based High Dose SRT / SRS B. Tas 1 , I.F. Durmus 1 , A. Okumus 1 , O.E. Uzel 1 1 Yeni Yuzyil University Medicine Faculty Gaziosmanpasa Hospital, Radiation Oncology, Istanbul, Turkey Purpose or Objective To evaluate correlation between Heterogeneity Index (HI), Gradient Index (GI), Conformity Index (CI) and size of metastases for high dose Stereotactic Radiotherapy/Radiosurgery (SRT/SRS) using Elekta Versa HD ® lineer accelerator with Agility ® collimator system. Material and Methods Twelve patients with single metastases were used in this study . For each of the patients, the target was defined on CT-MR fused images. Agility ® Multi Leaf Collimator system’s features were used for patients treatment planning. Minimum segment width adjusted 0.5cm, grid spacing adjusted 0.2cm and statistical uncertainty adjusted 1%. Patient’s treatment planning were performed using Monaco5.1 ® treatment planning system (TPS) with three or four non-coplanars 6 MV Flattening Filter Free (FFF) beams by partial Volumetric Modulated Arc Therapy (VMAT) tecnique for each patient. We determined four different size of metasteses catagory which are less than 0.5cc volume, between 0.5cc and 1cc volume, between 1cc and 5cc volume and between 5cc and 10cc volume. Also, five different plans were performed for getting different HI for each patients and maximum HI was restiricted 1.50. Results Correlations were determined between HI, GI, CI and size of metastases. Also, new Plan Quality Index (pQI) suggested for plan quality level of high dose Stereotactic Radiotherapy/Radiosurgery (SRT/SRS) plans. The mean lowest pQI was determined 6.60±0.3 for less than 0.5cc metastases volume, 5.28±0.7 for between 0.5cc and 1cc metastases volume, 4.57±0.2 for between 1cc and 5cc metastases volume and 3.29±0.2 for between 5cc and 10cc metastases volume. Conclusion Ideal one is the lowest GI and CI for good quality plan but GI and CI are not giving plan quality level exactly one by one. Therefore, we could determine plan quality level of treatment with pQI. Also, pQI depends on significantly size and HI of metastases especially for less than 1cc volume. When the metastases size is larger than 5cc, size of metastases and HI is losing its importance for pQI. Based on the correlation between HI, GI, CI and size of metastases we have decided that pQI should be ≤ 7.0 for less than 0.5cc metastases volume, pQI should be ≤ 6.0 for between 0.5cc and 1cc metastases volume, pQI should be ≤ 5.0 for between 1cc and 5cc metastases volume and pQI should be ≤ 4.0 for between 5cc and 10cc metastases volume for linac-based high dose Stereotactic Radiotherapy / Radiosurgery (SRT/SRT). PO-083 Adaptative radiotherapy for nasopharyngeal carcinoma L. Farhat 1 , W. Mnejja 1 , T. Sahnoun 1 , F. Dhouib 1 , J. DAOUD 1 1 EPS HABIB BOURGUIBA, Radiotherapy, SFAX, Tunisia Purpose or Objective Adaptative radiotherapy is a modification of the initial radiotherapy plan during the radiation course to re- optimize the treatment to take into account the anatomic variation such as the tumor response and weight loss.

Conclusion The results of this survey demonstrate that despite the recognised fundamental importance of H&NC research to care quality, many UK oncologists have limited or no time specifically allocated to this in their job plan. Many are not actively recruiting to national or local/non-portfolio trials, although there is willingness for greater involvement. The results provide useful insights into the constraints in H&NC research currently faced by clinicians within the NHS, which will need to be addressed in order to facilitate H&NC research in the future. PO-081 Recurrence analysis in head and neck squamous cell carcinoma treated with adjuvant EUD-based IMRT S. Welz 1 , T. Schönle 1 , D. Thorwarth 2 , D. Zips 3 1 Eberhard Karls University Tübingen, Radiation Oncology, Tübingen, Germany 2 Eberhard Karls University Tübingen, Biomedical Physics, Tübingen, Germany 3 Eberhard Karls University Tübingen, Radiatio Oncology, Tübingen, Germany Purpose or Objective Resected high-risk patients with squamous cell carcinomas of the head and neck (HNSCC) experience local recurrences in about 20% despite adjuvant radio- or radiochemotherapy. There is a paucity of data concerning the recurrence rates and sites in patients treated with IMRT, especially when planned with a Monte-Carlo algorithm based on an equivalent uniform dose (EUD) approach. We analyzed our data in this respect. Material and Methods We included all HNSCC (oral cavity, oropharynx and hypopharynx) patients from 2008 to 2012 who received a resection and completed an adjuvant IMRT of 60 to 66 Gy with or without a cisplatinum based chemotherapy. Follow up visits were scheduled at least every 3 months including CT scans. Recurrences were categorized as in-field, marginal or ex-field. Results 128 patients were included. Median follow-up was 24 months. 54% received adjuvant radiotherapy only, 46% had radiochemotherapy. Locoregional control was 94% with 2% only local, 2% local and nodal and 2% locoregional and distant recurrence. Of the 8 local recurrences, 3 were in- field, 4 were marginal and one was ex-field. Two-year overall survival was 79%, disease-free survival was 86%. Grade 1-2 acute toxicity occurred in 67% of the patients, grade toxicity 3-4 in 30%.