Abstract Book

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ESTRO 37

except for gender. Most of the CT-RRs (61%) were inside CTV3. No difference in location of recurrences, inside vs outside CTV3, was found between the centres (Pearson Chi-square p=0.6).

13 (56.5) 23 (100)

4 (16.7) 24 (100)

17 (36.2) 47 (100)

2-4

Total

Conclusion We reported a randomized phase III clinical trial to found that SW-IMRT is significantly better than ST-IMRT regarding subjective and objective assessment of swallowing dysfunction at 1,3 and 6 months post treatment. PV-0430 Localisation of recurrences in the neck after IMRT for HNSCC in relation to the elective CTV R. Zukauskaite 1,2 , C. Hansen 2,3 , J. Johansen 1 , C. Grau 4 , E. Samsøe 5 , E. Andersen 5 , J. Petersen 4 , J. Overgaard 6 , J. Eriksen 2,4 1 Odense University Hospital, Department of Oncology, Odense, Denmark 2 University of Southern Denmark, Institute of Clinical Research, Odense, Denmark 3 Odense University Hospital, Laboratory of Radiation Physics, Odense, Denmark 4 Aarhus University Hospital, Oncology Department, Aarhus, Denmark 5 Herlev Hospital, Oncology Department, Copenhagen, Denmark 6 Aarhus University Hospital, Department of Experimental Clinical Oncology, Aarhus, Denmark Purpose or Objective Loco-regional failures after curative radiotherapy (RT) for HNSCC are common despite combined treatment modalities and advanced RT techniques. The local failures appear predominantly in the high-dose treatment volume attributable to radioresistance of cancer stem cells. However, regional or N-site failures in the neck may additionally occur due to direct spread of cancer cells into lymphatics. The aim of the current study was to analyse the pattern of CT-verified regional recurrences (CT-RR) based on consecutive patients treated at three Danish university hospitals. Material and Methods We included 1,576 patients from three centres with laryngeal, oropharyngeal, hypopharyngeal and oral cavity SCC who completed curative IMRT during 2006–2012. The predominant treatment was 66-68Gy to the high-dose CTV, and 50Gy to elective treatment volume, CTV3, in 5- 6 fx/week with concomitant nimorazole and weekly low- dose cisplatin in case of regionally advanced disease and no contraindications. The CTV3 was contoured according to international consensus guidelines (Grégoire et al. 2003). Routine follow-up included videoscopy, and in one centre – additional ultrasound of the neck the first 2 years after treatment. CT or PET/CT was performed if clinically indicated, and the RR was expressed as point of recurrence origin (point within delineated RR volume with the largest distance to the recurrence surface). A deformable image registration propagated the recurrence points from recurrence-CT to planning-CT. Results After a median follow-up of 41 months (0-179), 1,382 patients were disease-free at N-site and 194 had regional failure, defined as RR or persistent disease two months after completed treatment. Out of 194 patients, 86, 18, 9, 81 had persistent regional disease, ultrasonography- verified, MRI-verified, and CT-RRs, respectively. Out of the 81 patients with CT-RRs, 16, 3, 28 a nd 34 had T1-2N0, T3-4N0, T1-2N+ and T3-4N+ disease, respectively, with a total of 108 RRs. The majority of recurrences appeared in patients with pharyngeal HNSCC and in ipsilateral levels II-III (Figure). The non-persistent patient groups containing CT-RRs (n=72) with successful image registration vs all other RRs (n=36) were similar in terms of patient, disease and treatment characteristics,

Conclusion Regional neck recurrences after IMRT for HNSCC appear predominantly in the elective treatment volume and in ipsilateral neck node regions. Assuming the same fraction of recurrences outside CTV3 for all patients with RRs as for patients with CT-RRs, only 2.9% (46/1,576) treated patients would experience a regional recurrence outside the contoured elective regions. Therefore, the guidelines seem to adequately cover the risk of lymphatic spread. PV-0431 Outcomes Differences in Taiwanese Patients with pT3 and pT4 Squamous Cell Carcinoma of the Tongue T.C. Yen 1 , C.T. Liao 2 , L.Y. Yang 3 , S.H. Ng 4 , L.Y. Lee 5 , C.Y. Lin 6 , H.M. Wang 7 1 Chang Gung Memorial Hospital, Nuclear Medicine, Taoyuan, Taiwan 2 Chang Gung Memorial Hospital, Otorhinolaryngology- Head and Neck Surgery, Taoyuan, Taiwan 3 Chang Gung Memorial Hospital, Biostatistics and Informatics Unit- Clinical Trial Center, Taoyuan, Taiwan 4 Chang Gung Memorial Hospital, Diagnostic Radiology, Taoyuan, Taiwan 5 Chang Gung Memorial Hospital, Pathology, Taoyuan, Taiwan 6 Chang Gung Memorial Hospital, Radiation Oncology,