ESTRO 36 Abstract Book

S574 ESTRO 36 2017 _______________________________________________________________________________________________

Purpose or Objective To report our finding that image-based diagnosis of recurrent nasopharyngeal carcinoma (rNPC) may not be real recurrence ， the "phantom tumor" phenomenon. Material and Methods From January 2010 to July 2016, we collected 16 cases of image-based diagnosis of recurrent nasopharyngeal carcinoma who have been subsequently confirmed to be not genuine recurrence by pathological biopsy or by the absence of EB viral load & long-term follow-up. Analysis was conducted for imaging features and clinical manifestations of these patients with images mimicking recurrence or residual lesion. Results There are 2 types of image patterns of this “phantom tumor”phenomenon. The most common one is characterized by extensive skull base lesions (11/16), and the other one is persistent or residual primary lesion (5/16). 13 cases were confirmed by pathological diagnosis (13/16), with histological findings of necrosis, inflammation, or granulation tissue. 3 cases had no pathological proof (3/16) and were judged to have no real recurrence/residual tumour by negative EBV DNA copy number as well as physical & fiberoscopic results. EBV viral load is 0 in 93.8% （ 15/16 ） of patients, and one did not have EBV viral load test.Nasopharyngeal necrosis by nasopharyngoscopy was noted in 56.3% （ 9/16 ） of patients, and cranial nerve palsy by physical examination in 43.8% （ 7/16 ） of patients. Conclusion Image-based diagnosis of recurrent nasopharyngeal carcinoma ， especially images showing extensive skull base involvement ， is unreliable, especially in T4 NPC patients. Some of these lesions are not real recurrence but benign pathological changes of the skull base including necrosis, inflammation or granulation tissue. Images showing persistent or residual primary lesions may also be misleading.Biopsy must be conducted with every effort to confirm recurrence or residual tumor. Without a pathological confirmation, the possibility of a “phantom tumor”is likely, and the final diagnosis must be made taking into account of endoscopic findings & EBV viral load. A second irradiation of a patient with a phantom tumor must be avoided which is certain to bring some irreparable damages or death to the patients. EP-1049 Intensity-Modulated Radiotherapy(IMRT) could provide better outcomes for nasopharyngeal carcinoma. P. Pattaranutaporn 1 , N. Ngamphaiboon 2 , T. Chureemas 2 , J. Juengsamarn 2 , S. Lukerak 2 , R. Sophonsakulchot 2 , C. Jiarpinitnun 1 1 Faculty of Medicine Ramathibodi Hospital- Mahidol University, Division of Radiation Oncology- Department of Radiology, Bangkok, Thailand 2 Faculty of Medicine Ramathibodi Hospital- Mahidol University, Division of Medical Oncology- Department of Medicine, Bangkok, Thailand Purpose or Objective Intensity-Modulated Radiotherapy(IMRT) has shown significant benefits for nasopharyngeal carcinoma in term of normal tissues sparing especially for the salivary glands. However, its benefit on treatment outcomes was controversy. This study was aimed to determine the treatment outcome benefits of IMRT over conventional radiotherapy in nasopharyngeal carcinoma. Material and Methods Stage I-IVb Nasopharyngeal carcinoma patients who treated with definitive radiation or chemoradiation at our hospital between 2007 and 2014 were identified through the cancer registry database. Patient characteristics, radiotherapy, chemotherapy and medical records were

retrospectively reviewed. Locoregional failure, distant failure and survival were analyzed in overall population and by radiation technique (Conventional vs IMRT). Results From 2007 to 2014, a total of 187 stage I-IVb nasopharyngeal carcinoma patients were treated with definite radiation or chemoradiation at our hospital. Of these, 107 and 80 patients were treated with conventional radiotherapy and IMRT, respectively. Conventional radiotherapy was mostly 3D conformal radiotherapy with 20 patients (18.69%) were 2D radiotherapy. Patient's characteristics and tumor stage were generally similar in both groups except patients with conventional radiotherapy had earlier year of treatment. Median follow-up time for survival were 64.7 and 37.8 months for conventional and IMRT groups. Radiation therapy was delivered in 180-200cGy per fraction for conventional radiotherapy. IMRT was usually delivered with Simultaneous Integrated Boost (SIB) technique with radiation dose per fraction ranged between 163-220cGy per fraction. Median total radiation dose were 7020cGy for conventional group and 6996cGy for IMRT group. 94.12% of patients received concurrent chemoradiation. 3-year locoregional failure (LRF) were 11.34% and 5.91% for conventional and IMRT group, respectively (p=0.2082). Disease-free survival (DFS) was marginal significant difference between conventional and IMRT group, 3-year DFS were 71.46% and 80.96% (p=0.0762). However, 3-year overall survival (OS) was not significant difference between conventional and IMRT group at 76.13% and 81.83%, respectively (p=0.2856). Conclusion In our experience, IMRT showed marginal significant DFS benefit and trended to have better locoregional control and overall survival. EP-1050 Prognostic factors analysis in advanced SCCHN treated by induction chemotherapy/local therapy C. Wu 1 , H.Y. Hsieh 2 , Y.C. Liu 2 , W.Y. Wang 3 , J.C. Lin 2 1 Changhua Show-Chwan Memorial Hospital, Radiation Oncology department, Changhua, Taiwan 2 Taichung Veterans General Hospital, Radiation Oncology, Taichung, Taiwan 3 Hung Kuang University, Nursing, Taichung, Taiwan Purpose or Objective To investigate the prognostic factors in patients with advanced squamous cell carcinoma of the head and neck (SCCHN) who received a novel weekly induction chemotherapy (IndCT) followed by local therapy Fifty patients with stage III/IV SCCHN were enrolled. Outpatient IndCT consisted of an uniform 4-drug regimens (cisplatin 60 mg/m2, day 1; docetaxel 50 mg/m2, day 8; 5-fluorouracil 2500 mg/m2 + leucovorin 250 mg/m2, day 15; epirubicin 30 mg/m2 + methotrexate 30 mg/m2, day 22; repeated every 4 weeks for 3-4 cycles). After finishing IndCT, local therapy including surgery, radiotherapy, concurrent chemoradiotherapy, or bio-radiotherapy was administered. Univariate and multivariate Cox proportional hazard model were used to identify significant prognostic factors. Analyzed variables included patient’s characteristics (age, gender, performance status), tumor factors (primary site, pathological differentiation, T-stage, N-stage), treatment factors (chemotherapy, surgery, radiotherapy) and pre-treatment FDG PET scan parameters (SUVmax of primary tumor, metabolic tumor volume [MTV], total lesion glycolysis (surgery/radiotherapy). Material and Methods

[TLG]). Results

After a median follow-up of 25 months, 13 patients experienced locoregional recurrence, 1 distant metastasis, and 1 both locoregional recurrence and distant