Abstract book - ESTRO meets Asia

S62 ESTRO meets Asia 2018

surgery alone and 2) the effect of adjuvant radiotherapy in the subgroup patients with pathologically risk features. Material and Methods Treatment outcome of 199 patients with previously untreated, biopsy-proven squmaous cell carcinoma of tongue, clinical stage T1-2N0M0 and received surgery alone between February 2007 and December 2014 were retrospectively analyzed. After obtaining significant prognostic factors, additional 23 patients with same condition who received surgery followed by adjuvant radiotherapy (RT) during the same study period were collected. We investigate the effect of adjuvant RT on loco-regional control in the subgroup patients with these risk features. Results After a medial follow-up of 89 months, there were 53 recurrences and 34 deaths among the 199 patients. The 5- year overall survival (OS) and loco-regional relapes free survival (LRFS) rates were 83.9% and 72.4%, respectively. Univariate analysis revealed that poor differentiated histology (p=0.0099), invasion depth over 5 mm (p=0.0028), tumor size over 2 cm (p=0.0001) and perineural invasion (PNI, p=0.0049) affected OS. Similarly, poor differentiated histology (p=0.0001), invasion depth over 5 mm ( p=0.0839), and PNI ( p=0.0721) affected LRFS. Other variables, including age, gender, smoking history, elective neck dissection, lymphovascular invasion, and close resection less than 3mm had no significant impacts on both OS and LRFS. Multivariate analysis showed that poor differentiated histology (p=0.0119) and tumor size (p=0.0056) were independent predictors for OS, but only poor differentiated histology (p<0.0001) could predict LRFS. Then, we select 3 risk features (poor differentiated histology, invasion depth over 5 mm, and PNI) and re- analyze outcome. The 5-year OS and LRFS were 91.7% vs. 71.0% (p=0.0002) and 77.5% vs. 64.3 % (p=0.0120) for patients with (n=75) or without (n=124) at least one risk factors (poor differentiated histology, invasion depth over 5 mm, and PNI). In the subgroup patients with risk features, adding postoperative adjuvant RT reduces relapse rates from 34.7% to 13.0% (p=0.0469). The locoregional relapse-free survival rates at 5-year were 84.0% vs. 64.3% (p=0.0473) for patients who received or not received RT.

Conclusion An overall relapse rate of 26.6% was observed for patients with early tongue cancer treated by surgery alone. Patients with pathologically risk factors (poor differentiated histology, invasion depth over 5 mm, and PNI) had significantly worse survivals. Adding postoperative adjuvant RT improved loco-regional control for those hig- risk patients. PO-157 Value of 18F-FDG-PET/CT and 131I-WBS in the detection of differentiated thyroid cancer progression T. Geliashvili 1 , A. Vazhenin 2 , N. Afanasieva 3 , E. Vasil’eva 4 1 A. Tsyb Medical Radiological Research Center – branch o f the National Medical Research Radiological Center of t he Ministry of Health of the Russian Federation A. Tsyb MRRC, Radiosurgical treatment with open radionuclides, Obninsk, Russian Federation 2 Chelyabinsk Regional Clinical Cente of Oncology and Nuc lear Medicine, Academician of the Russian Academy of Sciences- Profess or- Chief physician of the Chelyabinsk Regional Clinical C enter of Oncology and Nuclear medicine, Chelyabinsk, Russian Federation 3 Chelyabinsk Regional Clinical Center of Oncology and Nu clear Medicine, Radionuclide Diagnostiс, Chelyabinsk, Russian Federation 4 Chelyabinsk Regional Clinical Center of Oncology and Nu clear Medicine, Radionuclide Therapy, Chelyabinsk, Russian Federation Purpose or Objective Scientific research in the field of 18FDG-PET/CT visualization of thyroid cancer in Russia is unique. Therefore, the purpose of this study was to compare the diagnostic efficacy of 18 FDG-PET/CT and 131 I-whole body scintigraphy (WBS) in the detecting of differentiated thyroid cancer (DTC) progression during the monitoring of 82 patients were included between January 2011 and March 2017. The work is based on the results of 120 18 FDG- PET/CT and 120 131 I-WBS studies. 18 FDG-PET/CT examinations were performed on a positron emission tomograph combined with a 16-slice computer tomograph, Biograph 40 and 64, Siemens. Diagnostic 131 I-WBS (up to 5 mCi) was performed as an independent procedure. Post- therapeutic 131 I-WBS (after 33-135 mCi) was performed as a diagnostic step during each course of radioiodine therapy. Scanning was carried out on the single-detector combined treatment. Material and Methods