Abstract Book

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late toxicity (CTCAE) of the treatment were collected. Statistic analysis was performed using SPSS v. 24 and OS, DSS and rates of local control were assessed. Results The OS at 1 and 5 years was 87 and 53% respectively. The DSS at 1 and 5 years was 100 and 64,7% respectively. One patient had local relapse at 23 months past radiation treatment. The local control rate at 1 year was 100%. Six patients (26,1%) with secondary orbital adnexal lymphoma had disease progression, all of them in extra- orbital locations, after radiation treatment. They were then treated with systemic chemotherapy. None of the patients with primary ocular adnexal lymphoma had disease progression. Three patients had distant relapse.Of the 23 patients, 15 had primary ocular adnexal lymphoma. The median age at diagnosis was 73 years. Five (21,7%) older patients died of non-lymphoma related causes. Twenty-two patients had acute toxicity of radiation treatment: 3 with grade I-II and none with grade III-IV ocular edema, 2 with grade I-II and 3 with grade III-IV cutaneous pigmentation; 8 with grade I-II and 11 with grade III-IV cutaneous erythema; 1 with grade I-II and none with grade III-IV muscular orbital paresis; 5 with grade I-II and 2 with grade III-IV pain in the treated eye; 1 with grade I-II and none with grade III-IV xerophthalmia; 4 with grade I-II and 3 with grade III-IV conjunctivitis. Considering late toxicity, 6 patients had cataracts requiring surgery and 5 patients had xerophthalmia Conclusion Overall survival at 1 year was lower than in the literature (87 vs. 90-100%). Disease specific survival at 1 year was similar to the literature (100 vs. 100%).Local control rates were similar to the literature (95,6% vs. 90%). The local frequency of acute and late reactions was similar to the literature -95,6% vs. ~100%, and 47,8% vs. 50% respectively. The rarity of the disease, with multiple kinds of histologies, with reports of small patient numbers, makes interpreting comparative effectiveness of treatments challenging. We think is important to continue to characterize these patients and study the impact of radiation treatment in local control and survival. EP-1251 Teens who fall in-between – Pediatric or adult radiotherapy regimens in Hodgkin lymphoma A.Y. Lundgaard 1 , L.A. Rechner 1 , M. Lundemann 1 , N.P. Brodin 2 , M. Joergensen 1 , L. Specht 1 , L.L. Hjalgrim 3 , M.V. Maraldo 1 1 Rigshospitalet, Department of Clinical Oncology, Copenhagen, Denmark 2 Albert Einstein College of Medicine and Montefiore Medical Center, Institute for Onco-Physics, Bronx, USA 3 Rigshospitalet, Department of Pediatric Haematology and Oncology, Copenhagen, Denmark Purpose or Objective Hodgkin lymphoma (HL) is one of the most common cancers in adolescents-young adults, and 10-15% of cases presents in children. For patients aged 15-17 years, a pediatric or adult regimen can be chosen; however, the use of radiotherapy (RT) differs between the two approaches. In adult protocols, patients with limited disease all receive RT to the initially involved lymph nodes, 20 or 30 Gy depending on prognostic risk factors, whereas patients with advanced disease only receive RT to PET-positive lymph node remnants. In pediatric protocols, RT is given to patients with incomplete response to chemotherapy, regardless of initial stage, with 20 Gy to a modified involved field and a 10 Gy boost to PET-positive lymph node remnants. Consequently, the same patient can be treated applying a different volume as well as dose for the same initial extent of disease. The aim of this study is to describe the radiation dose delivered to the organs at risk (OARs) with pediatric or adult regimens, respectively, and estimate the associated

risk of life years lost (LYL) from radiation-induced late effects. Material and Methods All patients <18 years who received RT for HL from 2005- 2015 at our institution were included. For each patient, relevant OARs were contoured, the delivered plan re- calculated using the Acuros algorithm (v. 13.7.4), and the dosimetric parameters extracted. The estimated excess risk of radiation-induced cardiac disease and secondary cancers were calculated from dose-response models derived from childhood cancer survivors or HL series with long-term follow-up. Common scale late effects estimates were generated with the LYL model, which predicts the impact of the different late effects on life expectancy, while taking into account age at exposure, gender, and the prognosis of the late effect. Statistical analyses were performed with the Mann Whitney U test for non-parametric pairwise comparisons. Results Thirty-two patients were available for the analysis; 13 patients were treated according to a pediatric protocol, 19 with an adult. Patients treated according to a pediatric protocol generally had more advanced disease, with more adverse risk factors. The doses to the OARs are presented in Figure 1 and the corresponding LYLs are presented in Figure 2. Valvular heart disease and lung cancer contribute the most to LYL; in the pediatric group, stomach and breast cancer were also noticeable. Only thyroid and stomach cancer were significantly different.

Conclusion Despite a significantly lower dose to the treated volume for patients treated according to a pediatric protocol,