ESTRO 37 Abstract book

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ESTRO 37

Conclusion This is one of the first studies showing a significant relationship between radiotherapy for breast cancer and cardiac systolic and diastolic function. Interestingly, these effects are already observed relatively shortly after radiotherapy and with relatively low dose levels, confirming that there is no dose threshold for cardiac toxicity. This study confirms the importance of reducing the dose to the heart and may provide opportunities for secondary preventive measures. EP-1308 Radiotherapy after Immediate Breast Reconstruction with Implant is Safe J. Bjöhle 1 , E. Onjukka 2 , N. Rintelä 2 , S. Eloranta 3 , M. Wickman 4 , K. Sandelin 5 , G. Gagliardi 2 , A. Liljegren 1 1 Karolinska University Hospital, Department of Oncology- Pathology, Stockholm, Sweden 2 Karolinska University Hospital, Department of Medical Radiation Physics and Nuclear Medicine, Stockholm, Sweden 3 Scandinavian Development Services, Scandinavian Development Services, Stockholm, Sweden 4 Karolinska University Hospital, Department of Reconstructive Plastic Surgery, Stockholm, Sweden 5 Karolinska University Hospital, Department of Breast and Endocrine Surgery, Stockholm, Sweden Purpose or Objective To evaluate the clinical target volume (CTV) dose coverage when disregarding the dose received by the implant, and investigate whether immediate breast reconstruction (IBR) with implant (IBR+) is safe in terms of recurrence and overall survival (OS) in comparison with patients without implant (IBR-). Material and Methods All women diagnosed with breast cancer within the catchment area between 2009 and 2011 and receiving post-mastectomy radiotherapy (PMRT) were eligible for inclusion in the study. A matched-control cohort analysis including 128 patients with IBR+ and 252 IBR-patients (controls) was performed. Cox regression models were used to estimate the rate of recurrence among IBR+ women compared to IBR- women. The potential confounding effects of tumour stage and treatment were controlled for. Follow-up was calculated from the date of mastectomy until the date of first recorded recurrence, death or end of study at 30 th of June 2016, whichever came first. For IBR+ patients, the implant was removed from the CTV in the radiotherapy planning images, and the target coverage (V 95%: CTV covered by > the 95% isodose) was compared between the IBR+ and the IBR- Median follow-up duration was 5.8 years (0.1-7.5 years). No statistically significantly differences were found in the incidence of recurrence rate ratios or in recurrence free survival (log-rank p = 0.142), OS (log-rank p = 0.096) or breast cancer specific survival (log-rank p = 0.147) between the IBR+ and IBR- groups. When removing the implant volume from the CTV it was evident that V 95% was slightly lower for IBR+ patients compared to IBR- patients: in the group of patients without lymph-node irradiation the means were 84% and 92%, respectively. groups. Results

Conclusion Implant based breast reconstruction before radiotherapy leads to a slight underdosage of the target, due to the build-up effect. However, no correlation with a higher incidence of recurrence or decreased OS was seen in IBR+ patients compared to IBR-patients. The recommendation to offer immediate breast reconstruction to breast cancer patients receiving mastectomy is safe according to the present analysis. EP-1309 Myocardial segmental strain changes detected with cardiac MRI following tangential breast radiation S. Tang 1,2,3 , E.S. Koh 1,2,3 , J. Otton 3,4 , R. Rai 1,2,3 , S. Ananthapadmanachan 4 , L. Holloway 2,5,6,7 , D. Tran 4 , G. Delaney 1,2,3 , L. Thomas 3,8 , B. Schmitt 9 , G. Liney 6,10 1 Ingham Institute for Applied Medical Research, Cancer Outcomes- Research & Evaluation, Liverpool, Australia 2 Liverpool Cancer Therapy Centre, Radiation Oncology, Liverpool, Australia 3 University of New South Wales, Faculty of Medicine, Sydney, Australia 4 Liverpool Hospital, Department of Cardiology, Sydney, Australia 5 University of Sydney, Faculty of Physics, Sydney, Australia 6 University of New South Wales, Faculty of Physics, Sydney, Australia 7 Ingham Institute for Applied Medical Research, Radiation Physics, Liverpool, Australia 8 University of Sydney, Faculty of Medicine, Sydney, Australia 9 Siemens Healthcare Pty Ltd, Research and Innovation, Sydney, Australia 10 Ingham Institute for Applied Medical Research, MRI Physics, Liverpool, Australia Purpose or Objective Studies have documented acute subclinical changes following radiotherapy (RT)[1, 2]. Acute changes in myocardial strain have been reported in the left ventricle(LV) globally following RT. More recently strain reduction within the LV apex has been shown to correlate with apical mean radiation dose. This study aims to document early subclinical LV myocardial dysfunction following breast RT at the segmental level and correlate this to RT dose Material and Methods Twenty-two patients (mean age 59 years (38-76)) underwent tangential breast RT. Deep Inspiration Breath Hold(DIBH) was not used. No patient received chemotherapy. Nineteen patients received 42.4Gy/16Fr to the entire breast, 3 patients received 50Gy/20Fr. Cardiac MRIs were performed immediately prior to, and 6-8 weeks following RT. Single breath-hold SSFP cine acquisitions were acquired in the cardiac imaging planes on a 3T Skyra MRI (Siemens). 2D strain maps in the cardiac short and long axis, 3D strain maps were