ESTRO 38 Abstract book

S591 ESTRO 38

to perform a salvage surgery of the tumour located at the limit of bladder trigone - output of the right ureter, followed by postoperative HDR-BT in November 2011. Patient 3: a 11 months-old female affected with alveolar rhabdomyosarcoma at vesical neck classified at high risk group was initially treated induction chemotherapy in December 2017, resulting in partial tumour response after 2 different systemic lines. She underwent complete tumour resection and HDR-BT in July 2018. Results Patient 1 suffered from acute myeloblastic leukaemia in 2014; nevertheless, he currently is cured of both processes. Patient 2 relapsed locally after a year of treatment completion, so salvage total cystectomy needed to be done. Although the treatment of patient 3 has been very recent, she is free of disease at the first radiology control 3 months after treatment (follow-up is needed to see further results). Conclusion Multimodal approach in bladder conservative treatment with HDR – BT is a feasible alternative to total cystectomy in children. Although our experience is limited, the results could be comparable to those reported by the series of cases published in literature. PO-1062 brachytherapy in patients with bowen disease J.L. Munoz Garcia 1 , M.A. Gonzalez Ruiz 2 , J. Quiros Rivero 1 1 Badajoz University Hospital, Radiation Oncology, Badajoz, Spain ; 2 Punta de Europa Hospital, Radiation Oncology, Algeciras, Spain Purpose or Objective Purpose/Objective: High-dose-rate (HDR) brachytherapy, plesiotherapy modality, is a treatment option for Bowen disease (BD) patients with good oncologic outcomes. The objective of our study was to evaluate the initial results of BD patient treated in our centre in terms of local and cosmetic control . Material and Methods Material/methods: Observational, retrospective study of 12 BD lesions (12 patient) treated in our hospital from May 2015 to October 2017 with HDR brachytherapy using Valencia applicators, flaps and hand-made custom moulds (plesiotherapy). The treatment for all patients was delivered in 6 Gy fractions over seven sessions, two times a week, to a total dose the 42 Gy (EQD2 56 Gy; a/b10). Results Results: With a median follow-up of 32 months (range 19- 48), all patients had complete response and are alive (LC 100%). Only one patient presented a new lesion in a different area from the first location treated (DFS 90%). Most of the patients (67%) did not have acute toxicity; 4 patients (33%) developed erythema grade 2 and one patient (8.33%) developed conjunctivitis. One patient presented Ectropion as a late adverse event with regular cosmetic result (8.33%). 91% of patients had good or excellent cosmetic result with high level of satisfaction. Conclusion Conclusion: Our initial results in Bowen disease patient treated with High-dose-rate brachytherapy, plesiotherapy modality, shown and excellent local control, and disease free survival and cosmetic results. Brachytherapy hypofractionated regimen is a simple and cost-effective non-surgical attractive treatment option for the treatment of BD patients. PO-1063 Single-fraction low-energy electronic brachytherapy for conjunctival lymphoma G. Sarria 1 , C. Cabrera 2 , G.J. Sarria 2 , M. Buitrago 3 , P. Fuentes Rivera 2 , S. Serpa 3 , F. Giordano 1 1 Universitätsklinikum Mannheim, Strahlentherapie, Mannheim, Germany ; 2 Instituto Nacional de Enfermedades Neoplasicas, Radiotherapy, Lima, Peru ;

3 Instituto Nacional de Enfermedades Neoplasicas, Ophtalmic Oncology, Lima, Peru

Purpose or Objective Conjunctival lymphoma represents an uncommon tumor accounting for 5-10% of total extranodal lymphomas. Although radiotherapy is a frequent treatment option, limited capacities and lack of specialized centers are common problems in Peru, forcing radiation oncologists to apply short courses of radiotherapy. We here report a case series of patients treated with a novel single-shot scheme and also reviewed the literature for current short-course Three cases of conjunctival marginal zone (B-cell) lymphoma (MZL/MALT) of the fornix are presented. Following biopsy and sonographic assessment of the lesion thickness the application procedure was then carried out under topical anesthesia, blocking of the ocular musculature and fixing of the eyelids with a blepharostat. The head was then fixed in a thermoplastic mask, which was fenestrated over the affected eye. For brachytherapy, a low-energy X-ray device (50 kV maximum energy; Intrabeam, Carl Zeiss Meditec AG) equipped with a flat applicator was placed on the lesion, with light pressure to flatten the tumor. A focused single dose of 14 Gy kilovoltage brachytherapy, prescribed to the maximum thickness of the lesion was applied. This dose was chosen after calculating the equivalent dose of a 2 Gy fraction scheme (EQD2 = BED/[1+{2/ ⍺ /β}]) which, taking into account an approximate relative biological effectiveness (RBE) of 1.3and a tumor ⍺ /β ratio of 10 Gy, resulted in an EQD2 of 36.4 Gy. Follow-up was scheduled in quarterly intervals. irradiation strategies. Material and Methods

Results Due to the absorption properties of low-energy x rays, the dose to the lens was less than 4 Gy in the worst case scenario. After 16, 19 and 28 months of follow-up, none of the three patients treated exhibited acute or chronic toxicities and remained local or distant disease-free. Conclusion Single-dose kilovoltage brachytherapy was effective and safe in this small collective. Based on the literature, there