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 41

Glutamine delays oral mucositis in the head neck cancer patients. Moreover, it reduces the frequency and duration of grade 3 and grade 4 mucositis. More of the patients not receiving glutamine developed severe malnutrition when compared with those receiving this supplement, but there were no differences in other outcomes such as interruption of RT, hospitalization, use of opioid analgesics, or death during RT. Glutamine may have a protective effect during RT, reducing the risk and severity of OM, preventing weight loss, and reducing the need for nutritional support. PO-086 Brachial plexus position reproducibility for head and neck radiotherapy and it’s dosimetric impact S. English 1 , A. Thompson 1 1 North Middlesex University Hospital, Radiotherapy, London, United Kingdom Purpose or Objective Radiation-induced brachial plexopathy is a rare late complication of radiotherapy(RT) that can cause significant morbidity [1]. The Radiation Therapy Oncology Group recommends limiting the brachial plexus (BP) maximum dose to 60 to 66 Gray (2) Delineation of the BP and any dose constraints are defined at the point of radiotherapy planning. However, lack of reproducibility of patient position during RT treatment for example due to weight loss may lead to dosimetric uncertainties. The purpose of this retrospective study was to determine any change in position of the BP during head and neck RT treatment in relation to it’s original planned position and the dosimetric consequences of this. Material and Methods The study population consisted of 10 patients with oropharyngeal squamous cell carcinoma (OPSCC) treated with volumetric arc radiotherapy (VMAT) to a dose of 65Gy in 30 fractions over 6 weeks. Prior to commencing VMAT, patients underwent CT planning scan in a supine position in a 9-point thermoplastic mask. The treatment volumes and organs at risk (OAR) were delineated and a plan created using Eclipse Planning System. Treatment verification was achieved using weekly Cone Beam CT (CBCT) and daily KV imaging. For this retrospective study the brachial plexus position was delineated on each weekly CBCT. The position of the brachial plexus and the dose received was compared and re-calculated against the original planning scan. This resulted in 6 CBCT scans or data points for each of the 10 patients. Results The position of the BP varied on each weekly CBCT throughout treatment compared to the original planning scan. It’s most stable point was at the level of C5/C6 while most variation in position was observed around the T1 level. The results demonstrate an average dose increase of 4% to the minimum and mean brachial plexus dose over the course of the treatment equivalent to 2.6Gy. Conclusion VMAT allows us to plan and deliver high dose RT to achieve maximum Planning Target Volume (PTV) coverage whilst OAR dose constraints. The extent of OPSCC at both the primary site and nodal levels treated with radiotherapy impacts the maximum dose to the brachial plexus. However, any loss of reproducibility of patient position during RT may lead to uncertainty of dose delivered to both PTV and OAR. Therefore, a dose constraint to the BP may be exceeded. A recent study by Chen et al . (3) suggested a dose-response relationship for the development of brachial plexopathies with a 1.39 times greater odds ratio of developing symptoms with each 1Gy increase in the maximum BP dose. Our small study suggests that the actual dose received by

the BP may be higher than planned due to it’s variation in position throughout treatment. This may lead to increased risk of brachial plexopathy in this patient population. In order to avoid this risk there are a number of solutions that can be considered including; lower dose constraints on the brachial plexus, a margin on the BP volume to account for any positional change or adaptive planning again to account for any positional change. J. Schatteman 1 , D. Van Gestel 2 , D. Berwouts 1 , W. De Gersem 3 , I. Goethals 1 , L. Olteanu 3 , S. Rottey 4 , T. Vercauteren 3 , W. De Neve 3 , F. Duprez 3 1 Ghent University Hospital, Nuclear medicine, Ghent, Belgium 2 Jules Bordet Institute, Radiation oncology, Brussels, Belgium 3 Ghent University Hospital, Radiation Oncology, Ghent, Belgium 4 Ghent University Hospital, Medical Oncology, Ghent, Belgium Purpose or Objective To evaluate feasibility, disease control, survival and toxicity after adaptive 18 F-FDG-positron emission tomography (PET) guided radiotherapy in patients with recurrent and second primary head and neck squamous A non-randomized prospective trial investigated the feasibility of adaptive radiotherapy ± concomitant cetuximab in 10 patients with recurrent (n=5) and second primary (n=5) HNSCC. A primary endpoint of the study was to achieve a 2-year survival free of grade ≥3 late toxicity in ≥30% of patients. Three treatment plans based on 3 pre- and pertreatment PET/CT scans were consecutively delivered in 6 weeks. The range of dose painting was 66.0- 85.0 Gy in the dose-painted tumoral volumes in 30 fractions with fraction doses delivered to the tumor and/or positive lymph nodes of 2.2-3.5 Gy, 2.2-2.5 Gy and 2.2-2.5 Gy during fractions 1-10, 11-20 and 21-30, respectively. Patients were treated with static beam IMRT (n=6) or helical tomotherapy (n=4). If multidisciplinary decision for concomitant systemic therapy was taken, patients received a cetuximab loading dose (400 mg/m²) one week before start of radiotherapy (RT), followed by weekly doses of 250 mg/m² up to 6 times concomitant to RT. Twenty patients were planned to be recruited. Results Due to a slow accrual the study was terminated after the tenth patient. One patient did not complete the prescribed treatment course because of arterial bleeding during radiochemotherapy. Median dose of the initial RT was 67.6 Gy. Median time interval from initial RT to reirradiation was 6.3 years. Median follow-up time was only 5.2 months, reflecting the poor overall survival. One-year locoregional and distant control were 38% and 76%, respectively. Overall and disease-free survival at 1 year were 30% and 20%, respectively (Figure 1). No grade 4 or 5 acute toxicity was observed in any of the patients, except for arterial mucosal bleeding in one patient. Three months after radiotherapy, grade 4 dysphagia and mucosal wound healing problems were observed in 1/7 and 1/6 of the patients, respectively. Grade 5 toxicity (fatal bleeding) was seen in 2 patients, respectively at 3.8 and 4.1 months of follow-up. Late toxicity until 1 year of follow-up could only be assessed in 2 patients (Table 1). Data on 2-year grade ≥3 toxicity-free survival is not yet available; however, since only 20% of PO-087 Adaptive 18F-FDG-PET-guided reirradiation for recurrent and second primary head and neck cancer cell carcinoma (HNSCC). Material and Methods