ESTRO 38 Abstract book

S725 ESTRO 38

calculated for the two groups using the van Herk method. Dose statistics between groups were compared using a two tailed unpaired t test. Acute skin (RTOG), lung and oesophageal toxicity (CTCAE v 4.03) rates in the two groups were compared using the Mann-Whitney test. Results Eleven patients were treated with VMAT (three in free breathing (FB) and eight in vDIBH) nine patients were treated with WT(vDIBH). WT(vDIBH) required significantly longer total treatment times than VMAT (Table 1).

50 years (range 33-64 years) Fourteen patients (40%) completed chemotherapy before radiotherapy, five patients (14.3%) had trastuzumab and twenty-five patients (80.6%) had hormone therapy during radiotherapy course. At the time of analysis pre and post radiotherapy questionnaires were available for 30 patients (13 left sided; 17 right sided). Depression scores, health related quality of life and fatigue did not change significantly during radiotherapy treatment for both groups (see table1). Patients reporting severe fatigue (FACIT – Fatigue Scale score >7) were 2/30 (6.6%) before and 3/30 (10%) after radiotherapy. Interestingly only one of these patients received BH radiotherapy. Anxiety and depression level was higher than mean score in all patients.

All techniques were equally reproducible. There was no statistically significant difference in MHD or Heart V 17Gy between VMAT(vDIBH) and WT(vDIBH) (p=0.1269 and p=0.1490 respectively). There was no statistically significant difference in ipsilateral lung V 17Gy , mean contralateral lung dose or mean contralateral breast dose between the VMAT and WT techniques. The humeral head, oesophagus and thyroid all received a statistically significantly higher dose in the VMAT group when compared to the WT(vDIBH) group (see table 2). There were no statistically significant differences in skin or lung toxicity within 3 months of treatment. Increased rates of oesophageal toxicity were seen during the third week of treatment and two weeks post treatment in the VMAT group but this was not statistically significant (see table 3). One year lung, shoulder and oesophageal toxicity will be presented.

Conclusion The study is still ongoing. Preliminary results suggest that BH RT seems to not affect quality of life, psychological distress and fatigue in breast cancer patients undergoing radiotherapy. EP-1323 HeartSpare Plus: A comparison of the feasibility and acute toxicity of internal mammary chain RT A. Ranger 1 , A. Dunlop 1 , E. Donovan 2 , E. Harris 1 , N.M. DeSouza 1 , H. McNair 1 , A. Kirby 1 1 ICR and Royal Marsden NHS Foundation Trust, Clinical Oncology, Sutton, United Kingdom ; 2 University of Surrey, Centre for Vision Speech and Signal Processing, Guiildford, United Kingdom Purpose or Objective Inclusion of the internal mammary chain in the radiotherapy target volume (IMC_RT) improves disease free and overall survival in higher risk breast cancer patients but increases radiation doses to the heart. The HeartSpare Plus dosimetry study demonstrated that the use of either modified wide-tangential fields (WT(vDIBH)) or volumetric modulated arc therapy (VMAT(vDIBH)) in combination with voluntary breath hold was capable of reducing mean heart dose to below 4Gy in the majority of patients. The subsequent HeartSpare Plus clinical trial aimed to compare set-up reproducibility, the time taken to deliver IMC-RT using WT(vDIBH) versus VMAT including planning time, dose to target volumes and organs at risk (OAR), and acute toxicities associated with each technique. Material and Methods Twenty left sided breast cancer patients requiring IMC-RT were randomised to receive WT(vDIBH) or VMAT radiotherapy. Treatment times were compared using unpaired two tailed t tests with a significance level of 0.05 to detect a difference of 5 minutes per fraction between techniques. The population mean displacement (MD), systematic error (∑) and random error (σ) for CBCT chest wall matches in three planes of movement were

Conclusion In patients undergoing IMC_RT, VMAT(vDIBH) is quicker to deliver than WT(vDIBH)but is associated with more persistent acute oesophageal toxicity than WT(vDIBH). EP-1324 A Dosimetric Study of Heart and Lung Dose in Breast Radiotherapy-Our Institutional Experience C. Mccann 1 , E. Chow 2 , D. Vesprini 2 , L. Eric 2 , C. Paruag 3 , E. Lai 3 , M. Wronski 1 1 Sunnybrook Health Sciences Centre, Odette Cancer Centre- Radiation Therapy Program- Medical Physics, Toronto, Canada ; 2 Sunnybrook Health Sciences Centre, Odette Cancer Centre- Radiation Therapy Program- Radiation Oncology, Toronto, Canada ; 3 Ryerson University, Medical Physics, Toronto, Canada