ESTRO 2020 Abstract book

S985 ESTRO 2020

Conclusion Correlations between p16 protein level, HPV and EBV presence versus SUVmax and SUVmean values were insignificant. Further studies on a larger group of pts are needed. PO-1695 The utility of multiparametric MRI to characterize hypoxic tumor subvolumes compared to FMISO PET/CT N. Wiedenmann 1,2,3 , N.H. Nicolay 1,2,3 , M. Büchert 2,3,4 , H. Rischke 1,2,3,5 , J. Ruf 2,3,5 , L. Bielak 4 , L. Majerus 1 , M. Mix 2,3,5 , D. Baltas 1,2,3 , M. Bock 2,3,4 , A. Grosu 1,2,3 1 Universitatsklinik Freiburg, Department of Radiation Oncology- Medical Center University of Freiburg- Faculty of Medicine- University of Freiburg, Freiburg, Germany ; 2 German Cancer Research Center, Deutsches Krebsforschungszentrum DKFZ, Heidelberg, Germany ; 3 German Cancer Consortium DKTK, Partner Site Freiburg, Freiburg, Germany ; 4 Universitatsklinik Freiburg, Department of Radiology- Medical Physics- Medical Center University of Freiburg- Faculty of Medicine- University of Freiburg, Freiburg, Germany ; 5 Universitatsklinik Freiburg, Department of Nuclear Medicine - Medical Center University of Freiburg- Faculty of Medicine- University of Freiburg, Freiburg, Germany Purpose or Objective Monitoring of tumor hypoxia during definitive chemoradiation is indicated as persistence of tumor hypoxia is correlated with inferior prognosis and treatment resistance. This study investigates the utility of multiparametric MRI (mpMRI) to characterize hypoxic tumor regions by comparing FMISO PET/CT (FMISO PET) derived hypoxic and corresponding non-hypoxic reference tumor regions for tissue properties obtained by an integrated set of mpMRI biomarkers (T2*, ADC, ktrans, ve, and kep) in patients with head and neck squamous cell cancer (HNSCC) during the course of definitive chemoradiation (CRT). The aim was to identify mpMRI parameters that are linked to hypoxia and might be used as a surrogate for FMISO PET detected hypoxia. Material and Methods Patients with stage III-IVb HNSCC undergoing definitive CRT (total dose 70 Gy, 3 cycles cisplatin over 7 weeks) were enrolled for a prospective functional MRI and hypoxia PET/CT imaging study. Patients were prospectively imaged with serial FMISO PET and serial 3 Tesla mpMRI for T1w-, T2w-, transverse relaxation time T2*, and contrast- enhanced perfusion and diffusion-weighted measurements (ktrans, ve, ADC maps) in weeks 0, 2 and 5. Hypoxic tumor subvolumes (HSV) were generated using a 1.4 x meanSUV (standardized uptake value) normal tissue threshold applied to the FMISO PET. Non-hypoxic tumor subvolumes (nonHSV) were created as complementary subvolumes of the primary tumor. Mean values for mpMRI signal intensities within HSVs and complementary non-HSVs were compared by a paired samples t-tests (95% confidence interval) and additionally by the non-parametric Wilcoxon signed ranks test. Results Mean values for mpMRI parameters apparent diffusion coefficient ADC, transfer constant ktrans, interstitial volume fraction ve, and kep were calculated and compared by a paired t-test analysis between HSV and non- HSV for weeks 0, 2, and 5. ADC values were smaller within hypoxic tumor regions for all time points with the difference being significant at baseline and week 2 (p=0.007, p=0.004). Interstitial space volume fraction v e was significantly smaller for HSV than for non-HSV at baseline (p = 0.006). T2* and kep were not significantly different between hypoxic and non-hypoxic tumor regions at any time point (p=n.s.). Perfusion parameter ktrans was significantly lower in HSV as compared to non-HSV at baseline (p=0.035). Nonparametric Wilcoxon test confirmed significant differences for ADC at baseline and

free survival in all patients were 78.5% and 59.6%, respectively. Of the 41 patients, 25 (60.9%) showed complete response on follow-up studies. The median SUVmax of cervical cancer pre-and post-RT were 10.67 and 2.51, respectively. The median pTV of cervical cancer pre- , mid- and post-RT were 69.08 cm 3 , 6.28 cm 3 and 0 cm 3 , respectively. After RT for cervical cancer, the difference of reduction in SUVmax (median, 7.65) and pTV (median, 61.49 cc) were significant (p<0.001). There was a significant correlation between the pre-RT SUVmax and pTVRR between pre- and mid-RT. (median, 87.04%)(ρ=0.384, p=0.013). There was also a significant correlation between the SUVmax reduction rate (median, 76.8%) and the pTVRR (median, 100%)(ρ=0.393, p=0.011). Conclusion The SUVmax and pTV were significantly reduced after RT for cervical cancer. Further, between pre-and post-RT, the change of SUVmax in cervical cancer patients was significantly correlated with the change of pTV. These results indicated that pre-RT SUVmax in PET/CT scans has a potential role in assessing RT response in cervical cancer. PO-1694 PET/MR hybrid imaging in correlation with p16, HPV and EBV presence in head and neck cancer patients N. Samołyk-kogaczewska 1 , E. Sierko 2 1 Comprehensive Cancer Center of Białystok, Department of Radiotherapy, Białystok, Poland ; 2 Comprehensive Cancer Center- Medical University of Bialystok, Departament of Radiotherapy- Departament of Oncology, Bialystok, Poland Purpose or Objective Positron emitted tomography/magnetic resonance (PET/MR) is novel metabolic/morphological imaging method. There are limited number of small studies about the relationship between PET imaging with maximal and mean standardized uptake value (SUVmax and SUVmean) and human papilloma virus (HPV) status in head and neck squamous cell carcinoma (HNSCC) patients (pts). Very few studies concern the utility of PET/MR in characterization of HPV-related HNC, as well no data reporting correlation between Epstein-Barr virus (EBV) status and PET/MR features is available to date. The aim of our study was to assesed SUVmax and SUVmean parameters from PET/MR imaging in correlation with p16 protein, HPV and EBV Thirty eight HNSCC pts underwent both computed tomography (CT) and PET/MR examination. Based on the CT and PET/MR results 21 pts underwent surgical treatment as first-line therapy and were further include to present study. Contrast-enhanced CT was routinely performed in all pts on 64-detector row CT scanner (Aquilion CX). All pts underwent also PET/MR study on 3 Tesla Siemens Biograph mMR scanner (Siemens) after average of 9 days (range of 1 to 20 days) from CT. Maximal and mean SUV of the primary tumor was measured. Obtained postsurgical tissue material has been examined for evaluation of the expression of p16 protein, the latent membrane protein 1 (LMP1) expression as surrogate marker of EBV and presence of HPV genetic material. The verification of dependences between SUVmax and SUVmean value in relation to expression of p16 protein, HPV and EBV status was made with statistical analysis of obtained results. The level of significance was p <0.05. Relations between SUVmax, SUVmean versus p16, HPV, EBV presence were analysed with the use of t test. Results Average value of SUVmax in p16-positive pts was lower than in p16-negative pts (p=0,37). Maximal SUV was not significantly correlated with HPV and EBV status. Average values of SUVmean in pts with p16-, HPV- and EBV-positive were close to values in groups with p16-, HPV- and EBV- negative status. presence in HNSCC pts. Material and Methods