ESTRO 37 Abstract book

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ESTRO 37

Radiotherapy, tianjin, China 2 Tianjin Medical University Cancer Institute & Hospital, Department of Radiation Oncology, Tianjin, China Purpose or Objective Predicting distant metastasis after definitive treatment in nasopharyngeal carcinoma is problematic but critical for the decision of following treatment. This study aims to evaluate simulating CT features in predicting distant metastasis in nasopharyngeal carcinoma treated with definitive intensity modulated radiotherapy (IMRT) with or without systemic chemotherapy. Material and Methods 218 consecutive patients (between June 2011 and June 2015) receiving definitive IMRT were enrolled. The simulating CT images with intravenous contrast were collected. A total of 1039 imaging features, analyzed using both volume-averaged and voxelized methods, were extracted for each patients. Machine-learning methods were used to select best sets to predict distant metastasis in NPCs treated with definitive treatment. Results A total of 218 patients were enrolled, with a median age of 51 years old (10-73 years). 162 were male and 56 were female. All the patients received definitive IMRT, 151 patients (69%) treated with induction chemotherapy, and 140 (65%) patients with concurrent chemotherapy. With a median follow-up time of 32 months, 2 year distant metastasis free survival was 82%. A total of 1039 features were extracted, then 6 classifiers (SVM support vector machine, Logistic regression, KNN, decision tree, random forest, XGBoost) were used to select predicting sets and XGBoost performed best. The prediction accuracy, sensitivity and specificity were 0.83, 0.50 and 0.85. Conclusion Our results suggested that through a systematic analysis of CT features, imaging radiomics play a role in predicting distant metastasis in nasopharyngeal carcinoma, and should be further explored to help tailoring individually treatment. EP-1119 Comparison between T staging and FDG-PET for predicting outcomes of maxillary sinus carcinoma H. Doi 1,2 , M. Fujiwara 1 , K. Kitajima 3 , M. Tanooka 1 , T. Terada 4 , K. Noguchi 5 , R. Ishikura 1 , N. Kamikonya 1 , K. Yamakado 1 1 Hyogo College of Medicine, Department of Radiology, Nishinomiya, Japan 2 Kindai University Faculty of Medicine, Department of Radiation Oncology, Osaka-Sayama, Japan 3 Hyogo College of Medicine, Department of Nuclear Medicine and PET center, Nishinomiya, Japan 4 Hyogo College of Medicine, Department of Otolaryngology-Head and Neck Surgery, Nishinomiya, Japan 5 Hyogo College of Medicine, Department of Oral and Maxillofacial Surgery, Nishinomiya, Japan Purpose or Objective Concomitant intra-arterial infusion chemoradiotherapy (IA-CRT) has been used to treat locally advanced maxillary sinus squamous cell carcinoma (MSSCC) with positive outcomes. However, an optimal predictive prognostic factor for MSSCC treated with IA-CRT remains elusive. The purpose of this study was to assess the feasibility of 18F-fluorodeoxyglucose positron emission tomography (FDG-PET), including volumetric parameters, to predict prognosis for MSSCC treated with IA-CRT. Material and Methods Twenty-four patients with newly diagnosed MSSCC receiving FDG-PET imaging before IA-CRT treatment were analyzed in this retrospective study. All patients received radiotherapy with a total tumor dose of 60–66 Gy in a conventional fractionation schedule, using three- dimensional conformal radiotherapy or intensity-

modulated radiation therapy. Radiotherapy was performed concurrently with concurrent intra-arterial infusion chemotherapy (cisplatin). Results The response rate of IA-CRT was 83.33%, including complete and partial response in 11 and 9 patients, respectively. Of the 24 study patients, 7 (29.17%) died during the median follow-up duration of 24 months (range, 3–94 months). The 1-, 2-, and 3-year survival rates were 81.30%, 70.78%, and 64.34%, respectively. Fourteen patients (58.33%) experienced local failure. The median LC time was 9 months (range, 1–42 months). The 1-, 2-, and 3-year LC rates were 57.21%, 46.81%, and 40.96%, respectively. Of the 14 patients experiencing local failure, 8 patients received additional local salvage treatment (6 salvage surgery, 1 re-irradiation, and 1 intra-arterial infused chemotherapy). A summary of grade ≥3 acute toxicities attributed to IA-CRT is shown in the Table. 5 (20.83%) Regarding late toxicities, 1 patient had decreased visual acuity, 1 developed corneal ulceration, 1 developed blepharoptosis, 3 developed osteonecrosis, and 1 patient developed blindness due to an obstruction of the central retinal vein. Univariate analysis showed locoregional failure was associated with poor survival. In addition, T4b disease was associated with a high-risk of locoregional failure. Clinical T stage clearly stratifies local control among patients with clinical T3 or less, T4a, and T4b. Moreover, patients with T4b stage showed a significantly poorer local control when compared to stage T3 or less. Conclusion IA-CRT was well-tolerated and leaded good treatment outcomes in maxillary sinus squamous cell carcinoma. Pretreatment T stage predicts local control to IA-CRT, with FDG-PET showing no significant predictive information these patients. Dose escalation may be needed to successfully treat T4b disease. EP-1120 Early toxicity profile after re-irradiation with dose painting of head and neck cancer T. Skjøtskift 1 , C.D. Amdal 1 , M.E. Evensen 1 , T. Furre 2 , J.M. Moan 1 , T.V. Bogsrud 3,4 , E. Malinen 2,5 , E. Dale 1 1 Oslo University Hospital, Department of Oncology, Oslo, Norway 2 Oslo University Hospital, Department of Medical Physics, Oslo, Norway 3 Oslo University Hospital, Department of Nuclear Medicine, Oslo, Norway 4 Aarhus University Hospital, PET centre and Department of Nuclear Medicine, Aarhus, Denmark 5 University of Oslo, Department of Physics, Oslo, Norway Purpose or Objective Dose painting might have the potential to increase loco- regional control in head and neck cancer (HNC) without added morbidity. Recurrent or second primary disease, where the overlap with previously irradiated volumes is a problem, could benefit from dose painting as the focus is on delivering maximal dose to areas of high tumour burden while not exceeding dose constraints to organs at risk (OAR). In this study, we compare early toxicity between one group receiving our standard re-irradiation regimen and another Toxicity Grade Number of patients ( n = 24, %) Leukocytopenia 3 3 (12.50%) 1 (4.17%) Neutropenia Dermatitis Mucositis 3 4 3 1 (4.17%)