ESTRO 2021 Abstract Book

S836

ESTRO 2021

(p=0.003 and p=0.045, respectively). Regarding the pathologic lymph node distribution in the ipsilateral neck, in the cN0 patients, no significant difference was observed between p16- and p16+ patients (p=0.33 to 1); in the cN+ patients, the nodes were distributed in levels Ib, II, III, IV and V without differences between the p16- and the p16+ patients. In the contralateral neck of p16- patients, nodes metastases were mainly observed in levels II, III and IV, whereas for the p16+ patients, positive nodes were only observed in level II (p=0.03). Conclusion This study demonstrated the higher prevalence of cN+ and pN+ in p16+ OP-SCC patients, but without meaningful difference in the distribution of the lymph node drainage between p16- and p16+ OP-SCC. It indicates that no difference should be made between p16- and p16+ patients regarding the extend of neck treatment. PO-1005 Intensity-modulated radiotherapy for oropharyngeal carcinoma: oncologic and functional outcomes A. Nakajima 1 , S. Hiraoka 2 , M. Yoshimura 2 , Y. Matsuo 2 , T. Mizowaki 2 1 Kyoto University Graduate School of Medicine, Department of Radiation Oncology and Image-Applied Therapy , Kyoto, Japan; 2 Kyoto University Graduate School of Medicine, Department of Radiation Oncology and Image- Applied Therapy, Kyoto, Japan Purpose or Objective The purpose of this study is to retrospectively analyze the efficacy of definitive intensity-modulated radiotherapy (IMRT) for oropharyngeal carcinoma. Materials and Methods Between 2007 and 2017, a total of 80 patients with newly diagnosed oropharyngeal squamous cell carcinoma were treated with IMRT at our institution. Sixty-seven patients were male and 13 were female, and their median age was 64 years old (range: 39-91). The clinical stages (UICC 7th) were as follows: stage I in 2, II in 5, III in 12, IVA in 53 and IVB in 8. Thirty-four (43%) of tumors were p16+, 20 were p16- and 26 were unknown. The simultaneous integrated boost (SIB) technique was used to deliver 70/63/56 Gy in 35 fractions. Concurrent and/or induction chemotherapy was delivered in 50 and 44 patients, respectively. Cetuximab was administered concurrently in 13 patients. Overall Survival (OS), disease-free survival (DFS) and loco-regional control (LRC) rates were estimated using Kaplan-Meier method. Stimulated whole salivary flow was measured for 37 patients at baseline and posttreatment at 1,3,6,12 and 18 months by weighing a gauze pad before and 2 minutes after chewing (Saxon test; the low-normal value is 2 g). Wilcoxon signed-rank test was used to test for significant differences in salivary flow between different timepoints. Results The median follow-up period for surviving patients was 59 months (range, 11-139). The 5-year rates for OS, DFS and LRC were 78% (95% confidence interval [CI]: 68%-87%), 61% (95% CI, 50%-72%) and 72% (95% CI, 61%- 82%), respectively. The 5-year OS was 90% (95% CI, 80%-100%) and 67% (95% CI, 52%-82%) for patients with p16+ tumors and p16-/unknown tumors, respectively. During treatment, 38 (48%) patients required tube feeding. At 1year after treatment, 3 (4%) patients were still dependent on gastrostomy. Late toxicities ≥ grade 3 were observed in 11 patients (aspiration/dysphagia in 5, osteonecrosis in jaw in 2, laryngeal edema in 2, pharyngeal necrosis in 1, pharyngeal hemorrhage in 1 patient). Two patients had grade 5 aspiration pneumonia. Salivary flow declined from baseline to the lowest level at 3 months after completion of IMRT (p< 0.01, median: from 4.9 g to 0.99 g) and improved after 6 months (p<0.01 for all, median: 1.28 g, 1.86 g and 2.07 g at 6, 12 and 18 months, respectively) compared with that at 3 months. Conclusion Definitive IMRT for oropharyngeal carcinoma showed favorable oncologic outcome with acceptable toxicities. Although parotid gland and swallowing functions were impaired in the acute phase, they improved over time. PO-1006 Nutritional intervention in head and neck cancer patients undergoing (chemo-)radiotherapy A. Löser 1 , J. Abel 1 , L. Kutz 1 , A. Finger 1 , F. Greinert 1 , M. Sommer 1 , L. Krause 2 , G. Matnjani 1 , R. Schwarz 1 , S. Brackrock 1 , A. Krüll 1 , C. Petersen 1 , C. Carl 1 1 University Medical Center Hamburg-Eppendorf, Department of Radiotherapy and Radiation Oncology , Hamburg, Germany; 2 University Medical Center Hamburg-Eppendorf , Department of Medical Biometry and Epidemiology, Hamburg, Germany Purpose or Objective Radiotherapy alone or combined chemoradiotherapy favor the progress of malnutrition in patients with squamous cell carcinoma of the head and neck. Although malnutrition is known to negatively influence patients’ outcome, there is still a lack of prospective, randomized trials investigating the influence of the nutritional status on therapy-related toxicity and oncologic outcome. The aim of this study was to prevent increasing malnutrition under rardiotherapy or concurrent chemoradiotherapy through specialized and individualized nutritional counseling. Additionally, we investigated whether parameters from the so-called bioelectrical impedance analysis (BIA) may act as indicators for (threatening) malnutrition and oncologic outcome. Materials and Methods Between October 2018 and October 2020, 61 patients were randomized into an intervention and control group. Questionnaires (MUST, NRS-2002, and Nutriscore), clinical examinations, laboratory analyses, and bioelectrical impedance analysis (BIA) were used to assess nutritional status for all patients at the beginning and end of therapy as well as every 2 weeks during therapy. The intervention consisted of an individualized nutritional counseling every 2 weeks during therapy. Results For all patients, median baseline BMI was 23.8 (14.5-37.2) kg/m² and dropped to 22.9 (16.8-33) kg/m² after