6th ICHNO Abstract Book

page 46 6 th ICHNO Conference International Conference on innovative approaches in Head and Neck Oncology 16 – 18 March 2017 Barcelona, Spain __________________________________________________________________________________________ 6th ICHNO

was performed in general anaesthesia using systemic bleomycin (15.000 IU/m 2 ) prior to electroporation with sequences of 8 pulses of 100µs and 1000 V/cm applied voltage to electrode distance ratio. Evaluation of tumour response was assessed from PET/CT-, MRI- scans and biopsies. Primary objective was tumour response measured using RECIST criteria. Secondary objectives included tumour response in the treatment area from MRI and multiple time point FDG PET scans as well as patient evaluation of treatment using pain score and quality-of- life questionnaires (EORTC QLQ-C30 and QLQ-H&N35). Results Nineteen patients were included in this ongoing trial and treated for a recurrent carcinoma in the head and neck area. Due to large tumours, treatment could in most cases only be applied to parts of the tumour thereby leading to a debulking. Thirteen patients were evaluable according to RECIST criteria at evaluation 8 weeks after treatment. One patient died before evaluation. Five patients had cystic tumours at evaluation and therefore not evaluable according to RECIST criteria. Overall response in the 13 patients evaluable by REICST was 62% (8 of 13 pts): of these 2 (15%) had complete remission (CR), 6 (46%) had partial remission (PR), while progression (PD) was observed in 5 (39%). The MRI and PET results from the treatment area are currently being assessed. There was no change in pain score from baseline to evaluation. Quality-of-life questionnaires only demonstrated a change in dysphagia. Conclusion Electrochemotherapy was feasible in patients with recurrent head and neck cancer without further standard treatment options. Overall response rate was 62% with limited side effects, warranting continuation of the study.

volume; for organs at risk (OARs): maximum doses (D(max)) < 60 Gy to the brainstem, < 54 to the optic chiasm, < 50 to the optic nerves, <40 Gy to the eyes and < 5 Gy to the lenses. Dose was prescribed to the median dose according to ICRU 83. Dose-volume histogram, the maximum, minimum, and mean doses to the target volumes and organs at risk, and monitor units (MUs) were evaluated. Results VMAT offered a good tumor volume coverage and provided a good sparing of OARs (mean Dmax ipsilateral optic nerve:45,8 Gy, mean Dmax contralateral optic nerve: 43,3; mean Dmax optic chiasm: 46,4 Gy; mean Dmax brainstem: 37,9 Gy; mean Dmax ipsilateral eye: 47,6 Gy; mean Dmax contralateral eye: 33,3 Gy). VMAT showed low MUs (mean MUtot: 583,7) and low treatment delivery. Conclusion VMAT's plans further reduce doses to critical structures that are in close proximity to the target volume, and reducing treatment delivery time, decrease the effects of intrafractional uncertainties that can occur because of patient movement during treatment delivery. PO-097 Droplet Digital PCR for detection of circulating tumour DNA in blood of head and neck cancer patients J.H. Van Ginkel 1 , M.M.H. Huibers 1 , R.J.J. Van Es 2 , R. De Bree 3 , S.M. Willems 1 1 UMC Utrecht, Pathology, Utrecht, The Netherlands 2 UMC Utrecht, Oral and Maxillofacial Surgery and Head and Neck Surgical Oncology, Utrecht, The Netherlands 3 UMC Utrecht, Head and Neck Surgical Oncology, Utrecht, The Netherlands Purpose or Objective During posttreatment surveillance of head and neck cancer patients, imaging is insufficiently accurate for the early detection of relapsing disease. Free circulating tumor DNA (ctDNA) may serve as a novel biomarker for monitoring tumor burden during posttreatment surveillance of these patients. In this exploratory study, we investigated whether low level ctDNA in plasma of head and neck cancer patients can be detected using droplet digital PCR (ddPCR). Material and Methods TP53 Mutations were determined in surgically resected primary tumor samples from 6 patients with high stage (II- IV), moderate to poorly differentiated head and neck squamous cell carcinoma (HNSCC). Subsequently, mutation specific ddPCR assays were designed. Pretreatment plasma samples from these patients were examined on the presence of ctDNA by ddPCR using the mutation-specific assays. The ddPCR results were evaluated alongside clinicopathological data. Results In all cases, plasma samples were found positive for targeted TP53 mutations in varying degrees (absolute quantification of 4.2 – 422 mutational copies/ml). Mutations were detected in wild-type TP53 background templates of 7,667 – 156,667 copies/ml, yielding fractional abundances of down to 0.03%. Conclusion Our results show that detection of tumor specific TP53 mutations in low level ctDNA from HNSCC patients using ddPCR is technically feasible and provide ground for future research on ctDNA quantification for the use of diagnostic biomarkers in the posttreatment surveillance of HNSCC patients. Poster: Biology, HPV and molecular targeting

PO-096 Dosimetric evalutation of volumetric modulated arc therapy (VMAT) in sinonasal cancer raiotherapy E. Donini 1 , S. Magi 2 , S. Ricci 2 , E. Pasquini 3 , G. Frezza 1 1 Ospedale Bellaria - AUSL Bologna, Radiotherapy, Bologna, Italy 2 Ospedale Bellaria - AUSL Bologna, Medical Physics, Bologna, Italy 3 AUSL Bologna, Ear- Nose and Throat Metropolitan Unit, Bologna, Italy Purpose or Objective To assess dosimetric parameters of volumetric modulated arc therapy (VMAT) for nasosinusal malignancies with regard to the coverage of planning target volume (PTV) and the sparing of organs at risk (OAR). Material and Methods Nine patients with naso sinusal malignancies were treated with postoperative radiotherapy (VMAT, 2-3 non coplanar arcs) between 2015 and 2016. Seven patients were treated on primary target volume only (tumor bed), two patients required also nodal irradiation. Planning goals were the following: PTV: > 98% volume covered by >95% of prescribed dose; >107% of prescribed dose to < 2% PTV