ESTRO 37 Abstract book

S884

ESTRO 37

6 National Cancer Center Hospital, Radiation Therapy, Tokyo, Japan 7 Cancer Institute Hospital, Radiation Therapy, Tokyo, Japan 8 Shonan Kamakura General Hospital, Radiotherapy, Kamakura, Jersey 9 Nagoya University Hospital, Radiology, Nagoya, Japan 10 Japanese Red Cross Ise Hospital, Radiotherapy, Ise, Japan 11 Mie University Hospital, Radiation Therapy, Z, Japan 12 Kyoto Prefectural University of Medicine, Radiology, Kyoto, Japan 13 Kyoto University Hospital, Radiation Therapy, Kyoto, Japan 14 Osaka City General Hospital, Radiation Oncology, Osaka, Japan 15 Osaka University Hospital, Radiation Therapy, Osaka, Japan 16 Hyogo Prefectural Cancer Center, Radiation Therapy, Akashi, Japan 17 Hiroshima University Hospital, Radiation Therapy, Hiroshima, Japan 18 Kyushu University Hospital, Radiology, Fukuoka, Japan 19 Kurume University Hospital, Radiology, Kurume, Japan Purpose or Objective In 2013, childhood cancer core-center hospitals in Japan were selected to consolidate patients and improve treatment standards. Fifteen core-enters are selected, six of which are pediatric hospitals, eight are university hospitals, and the other one is municipal general hospital. In order to investigate whether patients were concentrated by making the core-center selection, we conducted a survey in the JASTRO research. Material and Methods We sent a questionnaire to each doctor responsible for pediatric radiotherapy by e-mail, and asked them to reply to the answered questionnaire. Questionnaire fills in the number of children who underwent radiation therapy under 15 years of age in each year according to International Classification of Childhood Cancer (ICCC-3,) and also fills in each year the period of no radiation treatment for children. Results As a result, the total number of patients in the three years (2010-2012) prior to the selection of 15 centers was 274, 285, 316, while in the 4 years after selection (2013- 2016) was 334, 342, 308, and 324 patients. There were fewer than 50 pediatric patients per year in each core- center. Since it is estimated that the number of pediatric patients irradiated at core-centers is about 1/3 that of childhood cancer patients in Japan, it is estimated that there are about 1000 pediatric radiation therapy patients in the country in 2016. Because of the small number of patients treated at each core-center, there are few institutions conducting radiotherapy for children without breaks for a year. From our survey, the patient concentration has not necessarily progressed after designation of a childhood cancer core-center hospital. Conclusion The future task is to prevent outcome-difference among core-center hospitals in pediatric radiotherapy. Childhood cancer patients are less likely to perform follow-up observations after treatment by radiation oncologists, so it is difficult to know the results including side effects after treatment. Even if an excellent radiation plan can be made, we will find that it is extremely difficult to fix and rest as planned for the actual irradiation. How precise radiotherapy is to be done

can’t be learned from textbooks and it is difficult to show how to handle it in a manual.

EP-1640 Impact of radiation therapy on outcome in high-risk neuroblastoma N. Bouzid 1 , D. Valteau Couanet 2 , S. Bolle 1 1 Gustave Roussy, Radiation Oncology Department, Villejuif, France 2 Gustave Roussy, Children and Adolescent Oncology Department, Villejuif, France Purpose or Objective To evaluate the impact of radiotherapy (RT) on local control (LC) and overall survival (OS) in patients with high-risk neuroblastoma (NBL) after multimodality treatment including high-dose chemotherapy (HD-CT). Material and Methods We reviewed the records of 78 patients with high-risk NBL treated in our institution according the HR- NBL1/SIOPEN protocol between 2003 and 2014. Results After HD-CT, 65 patients were eligible for RT. Thirty-nine received RT and 26 did not. Median dose to tumor bed was 21 Gy (range, 19,2-30,6 Gy). More patients in the RT group had gross residual disease than in the non-RT group (25,6% vs 7,7%). At a median follow-up of 38,5 months (range, 7-150 months), 28 patients died of disease (12 in the RT group and 16 in the non-RT group). Distant failure was observed in 20 patients of whom 13 after RT. Six patients who failed locally have presented synchronous metastasis, only one was initially treated with RT. In patients with macroscopic residue, one patient had local progression after RT while all patients did in absence of RT. 5-year LC rate were 90% in the RT group compared to 70% in the non-RT group (p=0,03). 5-year OS rate was 58% in the RT group compared to 32% in the non-RT group (p=0,014). Radiation-induced side effects were mainly hematologic and gastro-intestinal. No grade 3 or greater toxicity was noted. Conclusion Our data suggest that RT influence LC but also OS in high- risk NBL treated with multimodality therapy. A dose of 21Gy could be sufficient for local control in case of gross residual disease after HD-CT. EP-1641 Patterns of Recurrence after Radiation Therapy for High-risk Neuroblastoma J.H. Jo 1 , S.D. Ahn 1 , E.K. Choi 1 , J.H. Kim 1 , S.W. Lee 1 , S.Y. Song 1 , S.M. Yoon 1 , Y.S. Kim 1 , J.H. Park 1 , S.S. Kim 1 , J.H. Jung 1 1 Asan Medical Center- Univ. Ulsan, Radiation oncology, Seoul, Korea Republic of Purpose or Objective To investigate the patterns of recurrence in neuroblastoma patients who received radiation therapy We retrospectively analyzed patients with high risk neuroblastoma who received definitive treatment (chemotherapy, surgical resection, stem cell transplantation) with radiation therapy to primary tumor site, Between January 2003 and December 2015. Patients treated with three dimensional conformal radiation therapy or intensity modulated radiation therapy. A total 14 Gy – 24 Gy in 7 - 14fx was delivered to the planning target volumes which include the primary tumor bed and to primary tumor site. Material and Methods