Table 1: According to IRS V staging p<0.001 Relapse Patterns and Related Prognostic Factors After Radiotherapy in Childhood Rhabdomyosarcoma Serra Kamer¹, Meltem Öztürk¹, Eda Ataseven², Bengü Kadığolu³, Haldun Öniz⁴, Mehmet Kantar², Yavuz Anacak¹ ¹Ege University Faculty of Medicine Department of Radiation Oncology ²Ege University Faculty of Medicine Department of Pediatric Oncology ³Behcet Uz Children’s Hospital Department of Pediatric Oncology ⁴Tepecik State Hospital Department of Pediatric Oncology OBJECTIVES: To evaluate relapse patterns in rhabdomyosarcoma (RMS) patients after radiotherapy (RT). RESULTS: Most frequent histopathological subtype was embryonal in 45 (62,5%) Recurrence developed after radiotherapy in 19 patients (26.4%) (7 local and 2 lymphatic). Median time to recurrence was 31 months (range: 1-208). Median follow-up was 64 months (range: 2-208). 5-year overall and disease-free survival were 69.4% and 52.9% respectively. Table 1: According to IRS V staging p<0.001 In multivariate analysis, initial metastatic disease is related with lower survival (40.9 vs 80.6%, p<0.001). Long term side effects were recorded in 7 patients (growth delay in 4, permanent alopecia in 2), one patient with NF1 developed secondary tumor. MATERIALS AND METHODS: 72 patients Median age: 5(1-18) F/M: 0.67 IRS V STAGE LOW MEDIATE HIGH 5 YS 87,5 % 76,9 % 30,7 % 01/2001 - 12/2018 Tumor localization: Head and neck: n=31 (43%) Bladder: n=12 (16,7%) Genitourinary system: n=8 (11,1%) Extremities: n=6 (8.3%) Surgery: 50 patients (69.4%) Chemo.: 72 patients (100%) Concomitant CRT: 22 patients (30.6%) External RT: 51 patients (70.8%) Brachytherapy: 21 patients (29.2%) CONCLUSIONS: Radiotherapy is important part of the treatment in childhood RMS. Our results are similar to the other reports. Multidisciplinary approach is key to the successful management of RMS. Serra Kamer, MD Ege University Faculty of Medicine, Department of Radiation Oncology serra.kamer@ege.edu.tr