ESTRO 36 Abstract Book

S529 ESTRO 36 2017 _______________________________________________________________________________________________

IX was significantly correlated with overall stage (p=0.03) and N classification (p=0.04). There was a significant inverse correlation between MVD and CA-IX expression (r=- 0.22, p = 0.03). Multivariate analysis showed that low MVD combined with high CA IX-expression was a significant independent prognostic factor for worse loco-regional control (HR=2.6, 95%CI 1.1-5.0, p = 0.02) in the whole population. However, in the p16-positive subgroup, the difference was not significant (85.7% vs. 89.7%, p=0.73). Patients treated with CRT had a better LRC than those with BRT independent of MVD or CA-IX expression. Conclusion The combination of MVD and CA-IX status might give additional prognostic information in HNSCC patients with known HPV status. PO-0967 Analysis of tumour microenvironment using multi-parametric PET/MR imaging in HNSCC xenograft models S. Boeke 1 , R. Winter 2 , A. Menegakis 1 , P. Mena-Romano 2,3 , M. Krueger 4 , E.C. Sezgin 1 , G. Reischl 4 , B. Pichler 4 , D. Zips 1 , D. Thorwarth 2 1 University Hospital Tübingen, University Department of Radiation Oncology, Tübingen, Germany 2 University Hospital Tübingen, University Department of Radiation Oncology - Section for Biomedical Physics, Tübingen, Germany 3 Pontificia Universidad Católica de Chile, Institute of Physics, Santiago, Chile 4 Werner Siemens Imaging Center, Department of Preclinical Imaging and Radiopharmacy, Tübingen, Germany Purpose or Objective Hypoxia is a major determinant of outcome in radiotherapy (RT) especially in head and neck squamous cell carcinoma (HNSCC). Non-invasive imaging of tumour microenvironment with multi-parametric PET/MRI, using e.g. hypoxia specific tracers, is a potentially powerful technology for personalisation of RT. The aim of this study is to investigate simultaneously fMRI and hypoxia PET in HNSCC xenografts during the course of fractionated RT. Material and Methods FaDu tumours (n=7) were xenografted on the right hind leg of immunodeficient nude mice. After a growth period of 4-6 weeks multi-parametric FMISO-PET/MRI (7T, Bruker) was performed before and after RT (10 x 2 Gy in two weeks, small animal image guided RT platform, SAIGRT, Dresden, Germany). Following the second imaging, tumours were excised after injection of Pimonidazole and Hoechst for further histological analysis. The imaging protocol included a 80-90 min dynamic FMISO-PET acquisition, anatomical T2w and diffusion-weighted MRI (DWI, 9 b-values from 0 to 800 s/mm²) as well as DCE MRI. T2w anatomical MRI data was used for precise manual segmentation of the actual tumour region of interest (ROI). Within each tumour ROI, mean and maximum tumour-to-muscle ratios (TMR, TMR max ) as well as mean ADC values were analysed prior and post fractionated RT treatment. Results Two animals presented with very small tumor volume (< 10 mm³) which did not allow for ROI-based analysis before (n=1) or after (n=1) RT, respectively. The mean (SD) volume was 479.3 (651.7) and 808.0 mm³ (1146.3), mean ADC was 760.0 (138.3) and 950.0 10-³mm²/sec (176.9), mean TMR at 80 min post injection (pi) was 1.42 (0.27) and 0.98 (0.17) and mean TMR max at 80 min pi was 2.47 (0.18) and 1.75 (0.75) before and after 2 weeks of RT respectively (cf. figure 1). Mean changes (SD) during the two weeks of irradiation were 25.0% (71.64%), 19.7% (24.0%), -31.7% (10.5%), -21.5 % (86.9%) for tumour volume, ADC, TMR and TMR max , respectively.

Conclusion 111 In-girentuximab-F(ab’) 2 has a high affinity to CAIX. For optimal imaging of CAIX expression in human xenografts, a tracer protein dose of 10 microgram should be administrated 24 hours before scanning. These results suggest that 111 In-girentuximab-F(ab’) 2 is a promising tracer, in ongoing studies we will assess the tracer’s applicability for treatment selection and monitoring. PO-0966 Prognostic value of tissue necrosis,CD34 MVD and CA-IX in head and neck cancer patients D. Ou 1,2 , I. Garberis 3 , J. Adam 3 , P. Blanchard 1 , F. Nguyen 1 , A. Levy 1 , O. Casiraghi 3 , P. Gorphe 4 , I. Breuskin 4 , F. Janot 4 , S. Temam 4 , J. Scoazec 3 , E. Deutsch 1 , Y. Tao 1 1 Institut Gustave Roussy, Department of Radiation Oncology, Villejuif, France 2 Fudan University Shanghai Cancer Center, Department of Radiation Oncology, Shanghai, China 3 Institut Gustave Roussy, Department of Pathology, Villejuif, France 4 Institut Gustave Roussy, Department of Head and Neck Oncology, Villejuif, France Purpose or Objective Tumor hypoxia is adversely correlated to patient prognosis. The aim of the present study was to investigate the role of three hypoxia-related biomarkers in patients with locally advanced head and neck squamous cell carcinoma (HNSCC) treated with concurrent chemoradiotherapy or bioradiotherapy. Material and Methods In tumor tissue material from 100 patients with known HPV status, we evaluated the extent of tumor necrosis, the expression level of CA-IX and the microvascular density (MVD) measured as the density of CD34+ vascular structures. The Kaplan–Meier method, univariate and multivariate analyses, were used to analyze the correlations between biomarker status and clinicopathological characteristics and treatment outcomes. Results We found a significant correlation between MVD and overall stage (p=0.02) and T classification (p = 0.05). CA-