ESTRO 37 Abstract book

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ESTRO 37

Purpose or Objective Delay of postoperative radiotherapy (PORT) had potential to deteriorate treatment outcomes in high-risk head and neck squamous cell carcinoma (HNSCC). Relationship between treatment outcomes and delay of PORT was assessed. Material and Methods In our institution, PORT with or without concurrent chemotherapy was indicated for patients with positive margins (including suspicious margins), multiple lymph- node metastases, and/or extra-capsular invasion. Between May 2010 and September 2015, 39 patients with high-risk HNSCC received PORT. PORT doses were 50-66 Gy (mean 61.2 Gy), and 20 patients (51.2%) received concurrent chemotherapy. Intervals between surgery and initiation of PORT were 21-133 days (median 34 days) in all patients. Intervals were <35 days (21-35 days, median 28 days) in 21 patients (early PORT group) and >35 days (37-133 days, median 41 days) in 18 patients (delayed PORT group). Results Median follow-up time was 15 months. For the early PORT group and the delayed PORT group, 2-year overall survival rates were 89% and 48% respectively (p=0.0131), 2-year failure free survival rates were 68% and 41% respectively (p=0.0259), and 2-year locoregional-failure free survival rates were 80% and 61% respectively (p=0.0295). Conclusion Delay of PORT seemed to have a significant negative effect on treatment outcomes for high-risk HNSCC. EP-1125 Mandibular osteoradionecrosis (ORN) after curative reirradiation in head and neck cancer. L. Gutierrez Bayard 1 , M. Salas Buzón 1 , S. Garduño Sánchez 1 , M. Macías Lozano 1 , R. Rodríguez Sánchez 1 , E. González Calvo 1 , V. Díaz Díaz 1 , I. Villanego Beltrán 1 , J. Jaén 1 1 Hospital Universitario Puerta del Mar, Radiation Oncology, Cadiz, Spain Purpose or Objective Osteoradionecrosis (ORN) is a highly morbid sequel of radiotherapy in Head and Neck cancer. A recent analysis of oral cancer patients, demonstrated a non-significant trend of lower rate of jaw complications after IMRT (14%) compared with non-IMRT (17%). 3-DCRT we observed mandibular maximum point doses , but in IMRT a significantly larger part of the anterior mandible may be subjected to a ‘‘beam path” toxicity unobserved in 3- DCRT. Recently has been published that a range of DVH parameters mandibular V44 < 42% and V58 < 25% represent reasonable constraints for IMRT plan acceptability. We have the objective to study the incidence ORN in these head and neck recurrent tumors, previously irradiated, and if it correlates with these constraints. Material and Methods We evaluated 78 patients with recurrent disease, between 2005 to 2016. 33 larynx, 7 nasopharynx, 23 oropharynx, 6 hypopharynx and 9 oral cavity. The initial dose received 50-70 Gy 3-DCRT/IMRT (2-2.2Gy/fraction), 37/78 received radical radiotherapy,23/78 radical chemoradiation; other adjuvant radiotherapy, of which 10/ 78 was combined with chemotherapy. In 32/78 nodal recurrence (N1-N2), local 25/78 (T2-T4), 7/78 local+nodal recurrence, 14/78 seconds tumor, median age 59 year (range 42–79) . Reirradiation with external 3- DCRT/IMRT techniques/ and dose: 50-70 Gy. Results We identified 9/78 patients with ORN (11,53%) All of them in oropharyngeal and oral cancer patients (9/32: 28.12%). The ORN was graded as follows: grade I: minimal bone exposure requiring conservative management; grade II:

minor debridement received; grade III: hyperbaric oxygen needed; grade IV: major surgery required. Median follow-up time for all patients was 73 months (range 32–141); median time to development of ORN was 13 months from completion of second radiotherapy (range 3–59). The distribution of ORN grades was as follows: grade I (n = 2(22, 2%)); grade II (n = 3,( 33,3%)); grade III (n = 1, (11.1%)); and grade IV (n = 3,( 33,3%)). The mandibular mean dose (Dmean) in the ORN patients was significantly higher, but the maximum dose (Dmax) was not statistically different; 76.0 ± 3.5 Gy in ORN compared to 74.7 ± 2.9 Gy in non-ORN (p = 0.05). 1/9 (11.1%) patients with a V44 < 42% had ORN, 1/9 (11.1%) patients with V44 ≥ 42% and V58 < 25% had ORN, while 7/9 (77.78%) patients with both V44 ≥ 42% and V58 ≥ 25% had ORN. Conclusion Aggressive treatment of this disease recurring, allowing long survival, even in extensive disease is superior to best supportive care. In our serie ORN occurred primarily in the intermediate dose range of 35–75 Gy, In our study the incidence ORN correlates with with V44 and V58 as discriminatory parameters, so mandibular V44 < 42% and V58 < 25% represent reasonable DVH constraints for plan acceptability, when tumor coverage does not obviate their application. EP-1126 Target volume delineation of PET post one cycle of induction chemotherapy in oropharyngeal cancer C. Parkinson 1 , L. Pike 2 , S. Barrington 2 , T. Guerrero- Urbano 3 , M. Evans 4 , C. Marshall 5 , J. Staffurth 6 , E. Spezi 7 1 Cardiff University, School of Engineering, Cardiff, United Kingdom 2 King's College London, PET Imaging Centre, London, United Kingdom 3 Guy's Hospital, Clinical Oncology, London, United Kingdom 4 Velindre Cancer Centre, Clinical Oncology, Cardiff, United Kingdom 5 Cardiff University, Wales Research & Diagnostic PET Imaging Centre, Cardiff, United Kingdom 6 Velindre Cancer Centre, Radiotherapy & Clinical Trials, Cardiff, United Kingdom 7 School of Engineering, Cardiff University, Cardiff, United Kingdom Purpose or Objective FiGaRO is a feasibility study investigating the role of dose escalation based on 18 F-FDG-PET using intensity- modulated radiotherapy (IMRT) in patients with primary oropharyngeal tumours post one cycle of induction cisplatin and 5-fluorouracil (5FU) chemotherapy. In IMRT accurate delineation of the metabolic tumour volume (MTV) from PET imaging is critical to achieve highly conformal dose to the target volume whilst minimising dose to neighbouring organs at risk. Segmentation algorithms applied to 18 F-FDG PET imaging have an impact on the MTV. The aim of this study was to investigate the impact of automated segmentation techniques and their correlations with the MTV. Material and Methods Twenty-three patients were enrolled between October 2013 and March 2017. One patient was excluded as induction treatment resulted in too small an MTV for effective dose escalation and two other patients were excluded due to technical and unrelated medical problems. Twenty patients with squamous cell carcinoma (SCC) of the oropharynx were included. Patients received 1 cycle of neoadjuvant cisplatin and 5FU chemotherapy with repeat PET/CT imaging acquired at 3 weeks. 350MBq of 18 F-FDG was administered with scan acquisition at 90 minutes’ post injection. The metabolically active tumour volume was delineated by a nuclear medicine physician and a clinical oncologist to create a biological gross