ESTRO 37 Abstract book

S636

ESTRO 37

Zentrum München- Ingolstädter Landstraße 1- Neuherberg- Germany, Institute of Innovative Radiotherapy iRT, Munich, Germany

One patient presented with a grade 3 fatigue. One year after PT, data on 9 patients was available. No grade 3 or 4 toxicity was documented. Tumor control was achieved in 95.2% (n=20) of the patients. One patient developed osseous dissemination. So far, all patients are alive. Conclusion Early experiences suggest that PT is effective and feasible for the irradiation of adenoid cystic carcinoma. Data on acute and late toxicity is promising. However, longer follow-up and a larger cohort is needed to evaluate outcomes and toxicities on the long term. EP-1129 Perfusion CT in the evaluation of Nodal response after RCT in H&N cancers: a prospective study D. Delishaj 1 , S. Ursino 1 , A. Cristaudo 1 , F. Pasqualetti 1 , R. Morganti 2 , F. Matteucci 1 , E. Lombardo 1 , M. Cantarella 1 , F. Orlandi 1 , S. Montrone 1 , D. Baldaccini 1 , A. Gonnelli 1 , A. Molinari 1 , R. Mattioli 1 , E. Calistri 1 , P. Ferrazza 3 , L. Faggioni 4 , D. Caramella 4 , F. Paiar 1 1 Azienda Ospedaliero Universitaria Pisana, Radiotherapy, Pisa, Italy 2 Azienda Ospedaliero Universitaria Pisana, Section of Statistic, Pisa, Italy 3 Azienda Ospedaliero Provinciale di Trento, Radiotherapy, Trento, Italy 4 Azienda Ospedaliero Universitaria Pisana, Radiology, Pisa, Italy Purpose or Objective To report the initial results of a prospective study aimed at evaluating the CT perfusion parameter changes (ΔPCTp) of the primary gross nodal metastasis after radiochemotherapy (RCT) in head and neck cancer (HNCs) and to correlate with regional recurrence free-survival. Material and Methods Eligibility criteria included HNC (Stage III–IV) candidates for RCT. Patients underwent perfusion CT (PCT) at baseline and at 3 weeks and 3 months after treatment. Blood volume (BV), blood flow (BF), mean transit time (MTT) and permeability surface (PS) product were computed. Moreover, according to our internal protocol, PET/CT was performed at baseline and 3 months after treatment. The ΔPCTp were evaluated between baseline and 3-weeks/3-months, whereas PET/CT response was performed at baseline and 3 months after treatment. Results Between July 2012 and May 2016, overall 37 patients were enrolled in our study; among them 27 patients were evaluable for nodal response after RCT. Overall only 3 patients (11%) experienced tumor nodal recurrence (biopsy-proven) on the primary nodal site. A significant reduction of all the PCTp values (p<0,0001), except MTT (from 6,3 to 5,7 sec; p-value 0.089), was observed early at 3-weeks post-RCT compared to the baseline. Indeed, all PCTp values including MTT (from 6,3 to 2,3 sec; p=0,04), were significantly lower compared to the baseline values at 3-months after treatment. Moreover, a statistical significant correlation was observed between tumor nodal persistence and high BF values (p=0,045) at 3 months after treatment that did not result for the other Our preliminary findings seem to show that almost all PCTp are significantly reduced after RCT, whereas BF seems to come out as the strongest factor in predicting the regional recurrence free-survival. EP-1130 Influence of dose applied to cochlea during RT of vestibular schwannoma and its effect on hearing K.A. Kessel 1,2 , G.A. Bihoi 1 , M. Oechsner 1 , M.N. Duma 1 , S.E. Combs 1,2 1 Klinikum rechts der Isar- TU München, Department of Radiation Oncology, München, Germany 2 Institute of Innovative Radiotherapy iRT- Helmholtz parameters. Conclusion

Purpose or Objective To investigate whether the dose to the cochlea during radiotherapy (RT) of the vestibular schwannoma (VS) influences hearing preservation. Material and Methods From 2002 until 2015, 184 patients with VS were treated with fractionated stereotactic radiotherapy (FSRT, n=128) and daily image guidance, or stereotactic radiosurgery (RS, n=56). Median age was 60 years (range 16-85 years). Patients treated with FSRT were prescribed a median total dose of 53.4 Gy à 1.84 Gy, for RS a median dose of 12.2 Gy was applied. The treatment planning software iPLAN (Brainlab) was used to contour the cochlea and to calculate the applied dose retrospectively. We correlated the dosimetric results with the documented hearing preservation during follow-up graded according to the Gardner-Robinson scale. For comparison, we used the V x volume (V x = volume treated with x % of the prescribed dosage).

Results From the ongoing analysis, we are reporting on the first 134 patients analyzed (FSRT: n=90, RS: n=44). The median volume of the cochlea was 0.13 ccm for FSRT and 0.14 ccm for RS. The median min dose was 40.5 Gy for FSRT and 5.4 Gy for RS; the median max dose was 54.57 Gy for FSRT and 12.36 Gy for RS. Patients with a GR-scale of V (already deaf) before RT were excluded. We divided the FSRT group into two subgroups: group A consists of 58 patients whose hearing ability did not change after RT; group B includes 32 patients whose hearing ability degraded after RT. We calculated the median cochlea volume applied with V 75-100 of the prescribed dose. The results indicate that group B received a smaller dose to the cochlea, in comparison to group A. We also divided the RS group into two subgroups: group A consists of 27 patients whose hearing ability did not change after RT; group B includes 17 patients whose hearing ability degraded after RT. In contrast to the FSRT group, the results indicate that group A received a smaller dose to the cochlea than group B.