ESTRO 37 Abstract book

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ESTRO 37

optimize combining radiotherapy, chemotherapy and immunotherapy in the field of head and neck cancer. EP-1111 Reduction of target volume post induction chemotherapy using PET/CT in locally advanced HNSCC V. Rudzianskas 1 , S. Sediena 2 , E. Korobeinikova 1 , I. Kulakiene 2 , N. Jurkiene 2 1 Kaunas Medical University Hospital, Oncology and Hematology, Kaunas, Lithuania 2 Kaunas Medical University Hospital, Radiology, Kaunas, Lithuania Purpose or Objective Superiority of post-IC (induction chemotherapy) GTV (gross tumour volume) over pre-IC GTV still has not been tested. We assessed the results of patients with locoregionally advanced head and neck squamous cell cancer (LAHNSCC) treatment with IC following by chemoradiotherapy (CRT), using post-IC PET/CT images for IMRT planning. Material and Methods Two PET/CT were performed: one prior IC, and one 14 days after 3 cycles of IC (docetaxel 75mg/m2, cisplatin 75mg/m2 and 5-FU 750 mg/m2 day 1-5). The gross tumour volume (GTV70) and gross nodal disease (GTV60) on the post-IC PET/CT scans were contoured by the radiation oncologist working in cooperation with an experienced nuclear medicine physician.. The boost clinical target volume (CTV70) and nodal clinical target volume (CTV60) were obtained by GTV70 and GTV60 plus 5 mm respectively. The elective CTV (CTV50) included CTV70, CTV60 and bilateral elective lymphnodes. The margin of 3 mm was added for each CTV to create the planning target volumes (PTV70, PTV60 and PTV50). For high-risk volumes (PTV70 and PTV60) the prescribed doses were 70 Gy and 60 Gy respectively, for PTV50 – 50 Gy. CRT consisted of a chemotherapy with cisplatin (40 mg/m2 weekly) and RT (2 Gy once daily, 5 days a week). The primary end points was PFS. Secondary end points were OS and treatment toxicities. Acute toxicities were assessed using CTCAE v.4.0, late toxicities - using RTOG /EORTC criteria. Results 47 patients with histologically confirmed LAHNSCC (oro- and hypopharyngeal), HPV negative, KPS 70% and signed written informed consent approved by the Lithuanian Bioethics Committee. The mean follow-up period was 30.1 (7-55) months. The mean PFS was 38.8 months (95% CI, 33.1-44.6) and mean OS was 38.1 months (95% CI, 32.7-43.4). The 3-years PFS and OS rate were 59% and 52%, respectively. The most common acute toxicities of grade 3-4 were febrile neutropenia 13.4%, leucopenia 23%, mucositis 30.2%. Late toxicities of grade 3-4 were: dysphagia 4.2%, xerostomia 6.4% and osteoradionecrosis 2.1%. Conclusion This study suggests the efficacy of post-IC PET/CT based target volume delineation in selected patients undergoing IMRT for LAHNSCC. Further analysis is required to ascertain main clinical outcomes. EP-1112 The Effect Of Setup Error On Dose Distribution In Head And Neck Vmat Using Daily Igrt. S. Parente 1,2 , L. Ferella 1,2 , F. Vittorini 2 , M. Di Staso 2 , P. Bonfili 2 , P. Franzese 2 , E. Varrassi 2 , E. Di Cesare 1,2 , G.L. Gravina 1,2 , C. Masciocchi 1,2 1 Università degli Studi dell'Aquila, Divisione di Radioterapia e Radiobiologia, L'Aquila, Italy 2 Ospedale San Salvatore, Radioterapia, L'Aquila, Italy Purpose or Objective To assess the effect of patients setup errors identified with daily pretreatment CBCT imaging on dose the therapeutic schemes

distribution to target and OARs in H&N cancer treated with volumetric modulated arc therapy (VMAT). Material and Methods We analyzed eleven patients with advanced H&N cancer receiving VMAT. A retrospective study on setup error measurements was conducted on 334 CBCT images. The patient set up errors were defined as the offset between CBCT and planning CT in latero-lateral (LL), superior- inferio (SI) and antero-posterior (AP) directions. To evaluate the effect of patients setup errors on dose distribution, the isocenter of the original VMAT plans was shifted to simulate the dose to targets and OARs without online correction on planning CT. The magnitude of displacements in each direction was obtained using daily CBCT shifts. No optimization of beam profiles of the original VMAT plans was employed during re-planning process Dose-volume histograms (DVHs) were recalculated and were compared with planned DVHs; a difference ≥3% from planned dose was considered dosimetrically significant. Results A total of 334 CBCT images were acquired and analyzed and 1002 errors measurements in LL, SI and AP directions were recorded. Overall, the great majority of setup errors displacements was within the 3 mm threshold. Specifically, the relative frequency of setup errors < 3mm was 65% (LL), 65% (SI) and 45% (AP), respectively. The relative frequency of setup errors ≥ 3 mm was 35% (LL), 35% (SI) and 55% (AP), respectively. DVHs were recalculated for each OAR and compared with those obtained in the original planes .The wider discrepancy was found for right parotids glands (mean dose: 13,5%; 95%CI 11,1% to 15,8%), left parotids glands (mean dose: 11,3%; 95%CI 8,1% to 14,6%), brain stem (mean dose: 11,3%; 95%CI 8,58% to 14,1%), left cochlea (mean dose: 10,7%; 95%CI 7,1% to 14.2%). Spine, esophagus and mandible received a dose surplus lower than the before mentioned OARs. Moderate difference in target coverage from planned dose was recorded. . Conclusion Detection and correction of setup uncertainties are important for the precise delivery of radiotherapy treatment especially when modulated techniques are used. IGRT, by daily CBCT, may help in reducing uncertainties to a large extent ensuring a more accurate dose delivery to target volumes and sparing of OAR. EP-1113 Salvage surgery after organ preservation treatment for head and neck cancer J.A. Dominguez Rullan 1 , A. Hervás Morón 1 , M.C. Vallejo Ocaña 1 , M. Martín Martín 1 , R. Morís 2 , D. Sevillano 2 , S. Sancho García 1 1 Hospital Universitario Ramón y Cajal, Radiation Oncology, Madrid, Spain 2 Hospital Universitario Ramón y Cajal, Medical Physics, Madrid, Spain Purpose or Objective To evaluate the outcome of surgery after chemoradiation for locally advanced head and neck carcinoma. Material and Methods Between 2002 and 2014, 162 patients with locally advanced head and neck carcinoma were treated at our institution of which 33 patients underwent surgery after organ-sparing treatment. Laryngectomy-free survival and progression-free survival (PFS) were calculated using the Kaplan-Meier and logrank-test. Patterns of recurrence and loco-regional and distant failure were analysed. Results After chemoradiation 106 patients (70.7%) achieved clinical complete response and 44 patients (29.3%) had persistent disease after treatment. Thirty-three patients required surgery after chemoradiation; of these 17 underwent neck dissections (51.5%), seven primary tumor surgery (21.2%) and nine both (27.3%). In pathologic