6th ICHNO Abstract Book

page 54 6 th ICHNO Conference International Conference on innovative approaches in Head and Neck Oncology 16 – 18 March 2017 Barcelona, Spain __________________________________________________________________________________________ identifies the side and site of lymphedema for the purposes of intervention. and defining a volume for a radiotherapy boost merits further investigation. 6th ICHNO

PO-112 Role for interim PET in patient selection for dose escalation and boost volume definition in HNSCC? J. Lynch 1 , A. Nisbet 2 , C. Clark 2 , S. Whitaker 3 , K. Wood 3 1 Maidstone & Tunbridge Wells NHS Trust, Oncology, Maidstone, United Kingdom 2 St Luke's Cancer Centre, Medical Physics, Guildford, United Kingdom 3 St Luke's Cancer Centre, Head & Neck, Guildford, United Kingdom Purpose or Objective The aim of this prospective pilot study was to look at the feasibility and clinical value of performing an interim 18 F- FDG-PET-CT (iPET) in patients with head and neck squamous cell carcinoma (HNSCC). The spatial stability of the most FDG avid area of the tumour during treatment and the correlation of the data provided by pre- treatment, interim and post treatment scans with known prognostic factors and early survival was assessed. Material and Methods Eligible patients included those undergoing primary concomitant chemoradiotherapy (65Gy/30F) with weekly Cisplatin for Stage III/IV SCC of the Oropharynx. HPV status and smoking history was determined on enrolment. Each patient underwent a contrast enhanced planning CT and PET scan immobilised in the treatment position on consecutive days prior to the start of treatment and then again after 8 fractions of radiotherapy. A primary boost volume was defined according to 50% of the SUVmax of the tumour using the autocontouring function in the treatment planning system. A margin of 3mm was applied to this to provide a PTVboost. Results Eighteen patients (14M, 4F) fitting the above criteria were recruited. Mean follow up is 20 months. All patients completed their scans on schedule with the exception of one patient due to machine breakdown. A boost volume was successfully delineated on both pre- and interim scans using the above method in all except 3 patients where the SUVmax was not sufficiently higher than background on one or both scans to define an accurate volume. The SUVmax of the primary tumour on the initial scan was higher in the p16 -ve and patients with a smoking history of >10 years (Table 1). The results did not reach statistical significance, however when the patients who were p16 +ve with a smoking history of >10years were excluded from the p16 analysis then the difference between the positive and negative patients was greater (p=0.052). All except 3 patients showed a drop in SUVmax between the pre- and interim scans. The volume of the PTVboost reduced by an average of 49% between the two scans (29 – 100%). Two patients showed only very marginal increase which did not subsequently lead to an increase in the size of the PTVboost. One patient showed a big rise in their SUVmax (9.7 to 19.6). The volume of their PTVboost therefore increased by 99%. Their 12 week PET scan was deemed to show complete response but the patient subsequently had a local relapse 7 months after completion of treatment. Conclusion In comparison to other studies that have looked at the value of an iPET in patients with HNSCC this was a more tightly controlled study with a more homogenous group of patients. The results suggest the PET characteristics do correlate with known prognostic factors which has not been documented previously. The dual role of the iPET for identifying patients who may benefit from dose escalation

PO-113 Dynamics of biological imaging parameters in PW-MRI and FMISO-PET/CT during chemoradiation of SCCHN A. Bunea 1 , H. Bunea 1 , C. Stoykow 2 , L. Majerus 1 , N. Wiedenmann 1 , M. Mix 2 , P. Meyer 2 , M. Bock 3 , A.L. Grosu 1 1 Universitatsklinik Freiburg, Klinik für Strahlenheilkunde, Freiburg, Germany 2 Universitatsklinik Freiburg, Klinik für Nuklearmedizin, Freiburg, Germany 3 Universitatsklinik Freiburg, Medizinphysik, Freiburg, Germany Purpose or Objective Tumor hypoxia in squamous cell carcinoma of the head and neck (SCCHN) is related to poor prognosis. Reoxygenation during treatment leads to improved radiosensitivity. Adaptation of radiotherapy planning may allow for a more individualized treatment. The following study seeks to detected the dynamics of hypoxia during chemoradiation (RCTx) with FMISO PET/CT and correlated to perfusion MRI (PWI) parameters.PWI parameters can be correlated with tumor hypoxia and thereby have the potential to serve as predictors of treatment failure. In particular, the volume transfer constant between plasma and interstitial space Ktrans is an indirect measure of the capillary permeability and blood flow. High skewness of Ktrans is shown to be associated with improved treatment response, while tumors with low Ktrans have a poor prognosis (Shukla-Dave et al., 2012). A rise of Ktrans during RCTx is associated with a good response to treatment. Material and Methods We conducted a prospective imaging study in patients undergoing definitive RCTx (70 Gy, concomitant cisplatin) for HNSCC: in weeks 0, 2 and 5, 3-Tesla-MRI and FMISO PET were acquired. Tumor hypoxia was assessed in FMISO PET 2.5 h p.i. Gross tumor volume in MRI (GTVMRI) was defined as the area of high signal on T2-weighted images using the T1-weighted images for anatomic cross reference. Perfusion parameters Ktrans was calculated from dynamic T1-weighted MRI after contrast agent injection. MRI and PET scans were matched using iPlan contouring tool (v. 3.0.0, BrainLAB AG). Hypoxic subvolume (HSV) of GTVMRI was defined after normalization to the FMISO background in the contralateral sternocleidomastoid muscle, multiplied by 1.4. Volumetric parameters between weeks 0, 2 and 5 were compared and related to treatment response in terms of local recurrence (LR) and stable disease (SD). Statistical analysis was done with Spearman correlation. Before t-test analysis, normal sample distribution was confirmed with Shapiro–Wilk test. Results Between 2014 and 2015 10 male patients, treated for SCCHN with RCTx, were included. All received a total dose of 70 Gy. In total, 30 FMISO-PET/CT data sets and 27 MRI data sets were obtained. Mean follow up (FU) was 14.6 months (4 - 28 months). In weeks 0-5, patients with LR showed a mean Ktrans-decrease of 19%, whereas in weeks 0-2 an increase of SUVmax (57 %) was shown. Patients with SD showed Ktrans-increase (36 %) and SUVmax-decrease (- 61 %). HSV diminished in all patients. The correlation was significant between Δ GTVMRI and Δ Ktrans in week 0-2 (p=0.037) and between Δ SUVmax (week 0-5) and Δ Ktrans (week 0-2), p=0.045. Conclusion As was previously shown we conclude that changes in SUVmax are crucial in week 2. In our limited patient cohort and the short FU, we found that an increase in Ktrans might be related to improved outcome. Finding