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 11

A significant gain in regional control rate was observed in favor of ARCON. Both AR and ARCON are excellent strategies for larynx preservation in (moderately) advanced larynx carcinoma with good functional outcome.

target volumes and improved dose/volume metrics of organs-at-risk [7]. The results revealed considerable heterogeneity in patient-specific benefit from ART which was underestimated by reporting population-average. ART has been explored to investigate the limits of dose- escalation [8]. Quantitative clinical data of ART regarding toxicity reduction are scarce, if not inexistent. Conclusions: ICRU recommends generous inclusion of (presumably) diseased and normal tissue volumes in GTV, CTV and PTV. Evidence exists that more restricted PTV, CTV and GTV volume definition may translate to less toxicity without increasing recurrence rates. References 1. Daisne JF et al. Radiat Oncol 2014,9:121. 2. Longton E et al. Int J Radiat Oncol Biol Phys 2015,93:S71-S72. 3. Lin YW et al. PLoS One. 2015 Apr 28;10(4):e0125283. doi: 10.1371/journal.pone.0125283 4. Chen AM et al. Head Neck. 2014 Dec;36(12):1766-72 5. Samuels SE et al. Int J Radiat Oncol Biol Phys. 2016 Nov 1;96(3):645-52 6. Leclerc M et al. Radiother Oncol. 2015 Jul;116(1):87- 93. 7. Olteanu LA et al. Radiother Oncol. 2014 Jun;111(3):348- 53 SP-015 Prophylactic swallowing exercises in head and neck radiotherapy H.R. Mortensen 1 1 Mortensen Hanna Rahbek, Department of Oncology, Aarhus C, Denmark Abstract text While treatment of head and neck cancer has improved the survival rates over the past years, long-term morbidity plays an increasing role. One of the significant morbidities is long term radiotherapy-related dysphagia. Dysphagia is a symptom that covers many different problems often leading to serious consequences and greatly affecting patient’s quality of life. Different approaches have been taken towards reducing radiotherapy-related dysphagia including swallowing exercises implemented either as prophylactic exercises or reactive exercises. Publications on prophylactic swallowing exercises have emerged during the past few years but evidence is still scarce. Studies are heterogeneous according to study design, interventions, evaluation times, outcomes and how they are measured making a comparison complicated. A review of the literature shows, that the current studies mostly include few participants, only a few small randomized controlled trials, high risk of bias and not all exercises used have sufficient evidence for long-term improvement in swallowing. Endpoints include objective endpoints, observed-rated endpoints, patient-reported endpoints and clinical endpoints like tube feeding. Evaluation times ranged from a few weeks to several months. In general, most studies reports some positive results of swallowing therapy but the benefit is not consistent and not related to specific measures. Work is ongoing to elaborate on these differences. High rates of dropouts are a major concern when interpreting the studies and compliance to the exercises is generally poor. In conclusion, the evidence for prophylactic swallowing exercises for all patients being superior to therapeutic intervention in symptomatic patients is still scarce. To address the question properly larger studies are needed with minimal risk of bias, strong methodologies and an agreement on primary outcome, evaluation method and time.

Symposium: Reductions of radiation induced toxicities

SP-014 Target volume reduction W. De Neve 1 1 De Neve Wilfried, Belgium

Abstract text Radio(chemo)therapy (RCT) with curative intent for head and neck cancer (HNC) results in significant toxicity which is related to dose-volume parameters of target and surrounding normal tissues. Data on target-volume reduction as a strategy to reduce toxicity are scarce. Volumes for elective nodal irradiation are often manifold larger than volumes for gross tumour irradiation. A multicentre prospective randomised phase II trial investigated whether a 3-phase adaptive IMRT-scheme using reduced volumes of elective neck could reduce toxicity without compromising disease control compared to standard non-adaptive IMRT. In the experimental arm, elective sub-volumes were omitted if the population- based probability of subclinical disease was lower than ~7%. There were no significant differences in disease control, survival, acute or late toxicity and QOL between the experimental and the control arms. One patient in the experimental arm had regional recurrence in a region of the elective neck that would have been irradiated in the control arm. Volume de-escalation based on population- statistics are small, probably too small to yield relevant benefit regarding toxicity. Patient-individual volume de- escalation using sentinel lymph node mapping seems more promising. This could lead to a large volume de- escalation, as shown by Daisne et al. [1]. In this study, a significant reduction by factor of 2 of elective neck volume was achieved. Initial results of the ongoing phase II study of the same research group are promising, with the absence of any regional relapse in 22 patients at median follow-up of 14 months [2]. The utility of PTV- margins > 0 mm around elective neck volumes is debatable. Clinical target volumes around GTV or tumour bed are based on educated guess rather than on scientific evidence. Surveys demonstrate large variations in GTV- delineation with no reports that smaller delineations change the rates or locations of recurrences. Reducing the high-dose CTV in nasopharyngeal cancer did not negatively affect survival rates but did reduce the late xerostomia events [3]. The use of reduced (5 mm ->3 mm) CTV-to-PTV margins in HNSCC was associated with reduced late toxicity while maintaining loco-regional control [4]. In oropharyngeal cancer, a planning study showed significant NTCP-reduction for ipsilateral parotid and contralateral submandibular glands by omitting the PTV-margin [5]. GTV is the union of volumes of malignancy demonstrable by imaging and clinical examination. 18FDG-PET translated to smaller GTV sub-volumes for the primary tumour than CT. PET-based planning demonstrated an improvement on dosimetry by lowering dose to organs at risk [6]. This information has been clinically investigated to dose-escalate volumes smaller than the multimodality GTV but not yet to reduce dose to low-avidity parts of the multimodality GTV aiming at reducing toxicity. Clinical data exist on the use of tumour regression in adaptive radiotherapy (ART) to treat smaller GTVs, CTVs and PTVs. ART increased minimum and decreased maximum doses in