ESTRO 36 Abstract Book

S522 ESTRO 36 2017 _______________________________________________________________________________________________

1 General Hospital Polonnaruwa, Clinical Oncology, Polonnaruwa, Sri Lanka 2 The Christie NHS Foundation Trust, Clinical Oncology, Manchester, United Kingdom Purpose or Objective Optimal radiation dose delivery in lung cancer patients is limited by the risk of toxicity to adjacent organs especially the heart, lung and spinal cord. Post-treatment lymphocytopaenia is a recognised complication in patients undergoing thoracic radiotherapy and if severe, can lead to opportunistic infections. We hypothesised that a higher integral heart dose is associated with post-treatment lymphocytopaenia in patients with small cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC) treated with radical radiotherapy. Material and Methods 138 patients (103 NSCLC and 32 SCLC) treated with radical radiotherapy were included in this study. Concurrent chemotherapy was administered in 85/135 patients. Prescribed dose to planning target volume ranged from 41.4 to 72 Gy with a median of 66 Gy. Lymphocyte counts prior to treatment and up to 100 days post-treatment were obtained. The integral heart dose was derived by using the product of mean dose and volume. A linear mixed effects model, incorporating the following variables: integral heart dose, integral heart dose per fraction, baseline lymphocyte count, time from start of treatment and use of concurrent chemotherapy was used to analyse the effect on post-treatment lymphocyte counts Results The median integral heart dose in the cohort was 14.5 Litres-Gy (range 4-35.6). Integral heart dose (p=0.03) and time from start of therapy (p < 0.001) were negatively correlated with post-treatment lymphocyte counts while integral heart dose per fraction (p=0.05) and baseline lymphocyte count (p<0.001) were positively correlated. Use of concurrent chemotherapy was not statistically significant in the model. Conclusion Total integral heart dose predicts a lower post-treatment lymphocyte count in lung cancer patients treated with radical radiotherapy. The positive correlation with higher integral heart dose per fraction suggests that fractionation has an adverse effect on post-radiotherapy lymphocyte counts. PO-0953 Proteome profiles in PDAC patients with local recurrence after postoperative radiochemotherapy L. Bolm 1 , V. Oria 2 , L. Kaesmann 3 , P. Bronsert 4 , U.F. Wellner 5 , O. Schilling 6 , D. Rades 3 1 University of Luebeck, Department of Radiation Oncology- Department of Visceral Surgery, Lübeck, Germany 2 University of Freiburg, Department of Molecular Medicine and Cell Research, Freiburg, Germany 3 University of Luebeck, Department of Radiation Oncology, Luebeck, Germany 4 German Cancer Consortium DKTK and German Cancer Research Center DKFZ, Department of Pathology, Heidelberg, Germany 5 University of Luebeck, Department of Visceral Surgery, Luebeck, Germany 6 German Cancer Consortium DKTK and German Cancer Research Center DKFZ, Institute of Molecular Medicine and Cell Research- Freiburg, Heidelberg, Germany Purpose or Objective Complete surgical resection remains the only curative option in patients with pancreatic ductal adenocarcinoma Poster: Radiobiology track: Radiobiology of the intestinal track

PO-0951 Episcleral Brachytherapy for Uveal Melanoma A. Ponte 1 , T. Teixeira 1 , I. Nobre-Góis 1 , J. Casalta-Lopes 1 , P.C. Simões 1 , A. Cavaco 1 , J. Veríssimo 2 , R. Proença 2 , M. Borrego 1 1 Hospitais da Universidade de Coimbra, Serviço de Radioterapia, Coimbra, Portugal 2 Hospitais da Universidade de Coimbra, Serviço de Oftalmologia, Coimbra, Portugal Purpose or Objective Uveal melanoma is the most common intraocular tumor in the adult age, and the second most common after skin melanoma, with an annual incidence rate of 4-10 per million people. Until November 2013 portuguese patients with uveal melanoma were sent abroad for treatment. Different therapeutic approaches include enucleation, proton therapy, episcleral brachytherapy (EBT), with similar outcomes. The purpose of this work was to evaluate treatment response in patients with uveal melanoma submitted to EBT. Material and Methods Included all patients with uveal melanoma treated in our institution by the Radiation Oncology Department in co- operation with the Ophthalmology Department, between November 2013 and September 2016. Plaques with low energy photon seeds ( 125 I) were used. Dose prescription was 85 Gy to the tumor apex. Response was evaluated by ophthalmic ultrasound with serial lesion measurements and treatment side effects were recorded. A type I error of 0.05 was considered for inferential statistics. Results 50 EBT procedures were done in 50 patients, with a median age of 64 years, female gender (58,0%) and right eye (62,0%) predominance. Initial median diameter and thickness were 12,23 mm (5,92 to 18,70 mm) and 6,73 mm (2,60 to 12,67 mm), respectively. No distant metastatic disease was present at the time of diagnosis. Staging was as follows: Stage IIB 50,0%, Stage IIA 44,0% and Stage IA 4,0%. The median treatment time was 140,7 hours, with a median prescribed dose of 85,90 Gy. A notched eye plaque (ROPES15n) was used in 26,0% of cases. No complications during implant procedure or treatment period were registered. The median follow-up was 10,5 months (1 to 33 months). During this period, a significant reduction in thickness (median difference of 2,035 mm, p<0,001) and diameter (median difference of 2,43 mm, p<0,001) was recorded. Radiation retinopathy was observed in 20,0% of patients, treated by intra-ocular anti-VEGF injection in all cases. Tumor relapse occurred in 2 patients (4,0%) and distant spread in one of these. No cancer related death was EBT is an effective and well tolerated eye sparing method to treat patients with uveal melanomas. A progressive significant reduction in tumors dimension was observed. No severe late side effects was registered, although follow-up time is still limited. registered. Conclusion

Poster: Radiobiology track: Normal tissue biology of the heart

PO-0952 Integral heart dose and lymphocytopaenia in lung cancer patients treated with radical radiotherapy N. Joseph 1 , A. McWilliam 2 , K. Haslett 2 , J. Kennedy 2 , C. Faivre-Finn 2 , A. Choudhury 2