ESTRO 36 Abstract Book

S160 ESTRO 36 2017 _______________________________________________________________________________________________

currently not any deformable registration algorithms which have shown performance in sigmoid and bowel which is sufficent for dose accumulation. In conclusion, DVH addition is currently recommended by the ICRU 89 report for dose summation in brachytherapy, and provides in most scenarios a good accuracy for assessment of total dose in targets and in organs such as bladder and rectum. Dose summation in highly mobile organs such as sigmoid and bowel is currently related with significant uncertainties, and there could be potential to improve this with appropriate DIR algorithms. SP-0312 Imaging and fusion techniques for focal brachytherapy L. Beaulieu 1 1 Laval University - Faculty of Science and Engineering, Université laval Cancer Research Centre, Québec City, Canada Over the last decade, numerous technological developments have made brachytherapy one of the most precise needle-based procedures on the market. The cornerstone of interstitial brachytherapy for many years now has clearly been real-time ultrasound (US) image- guidance and more recently real-time 3DUS image- guidance. From whole gland prostate cancer treatments to focal boosts and now focal therapy, brachytherapy is head of the curve of any other prostate focal therapy modality at this time in terms of precision and accuracy. However, current standard US-guidance is not sufficient for focal therapy; our real-time image-guidance technique needs to be supplemented with more information. This presentation will look at the role of multi-parametric MRI in prostate focal therapy as well as US-augmented with MRI for real-time guidance. This brings the notion of augmented reality as well as the challenge of image fusion among two very different imaging modalities and image sets also taken under very different conditions. We will also discuss the topic of merging tissue information (e.g. biopsy) with imaging data to provide a complete cancer burden maps for targeting purposes. Finally, we will provide a forward-looking view of real-time multi- parametric 3DUS guidance and targeting for such procedures. OC-0313 What is the effect of axillary treatment on patient reported outcomes in breast cancer patients? M.L. Gregorowitsch 1 , H.M. Verkooijen 1 , N. Fuhler 1 , D.A. Young Afat 1 , A.N.T. Kotte 1 , M. Vulpen van 1 , C.H. Gils van 2 , D.H. Bongard van den 1 1 University Medical Center, Radiation Oncology, Utrecht, The Netherlands 2 Julius Center for Health Sciences and Primary Care- University Medical Center, Epidemiology, Utrecht, The Netherlands Purpose or Objective In breast cancer patients with limited (sentinel) lymph node involvement, axillary lymph node dissection (ALND) is increasingly being replaced by axillary radiotherapy. Since ALND is associated with a high risk of upper-body morbidity, axillary radiotherapy might be favorable in patients with limited lymph node involvement. However radiation-induced morbidity can also influence quality of life, the extent of which may depend on the irradiated volumes. We compared patient reported outcome measures (PROMs) of breast cancer patients at the start adjuvant radiotherapy, during and after radiotherapy according to the extent of axillary treatment. Material and Methods Proffered Papers: Breast and gynaecology

This study was conducted within the Dutch UMBRELLA cohort (i.e. prospective observational cohort including breast cancer patients indicated to receive adjuvant radiotherapy at the department of Radiation Oncology at the University Medical Centre Utrecht). All participants consented to collection of clinical data and patient reported outcomes (PROMs). Arm function and Quality of Life (QoL) were measured by EORTC QLQ-C30 and BR23. We first compared differences in mean PROM scores between patients who underwent ALND and those who did not by two sample t-test. In a second step, we estimated the effect of extent of axillary radiotherapy on PROM scores in patients stratified on ALND, and used analyses of variance (ANOVA) to test for differences. Finally, we compared patients who underwent ALND and local RT with non-ALND patients treated with axillary RT to estimate the differences between axillary RT and ALND. Results Between October 2013 and December 2015, 521 patients were enrolled. In total 75% (n=390) of the patients were treated with local radiotherapy on the breast/chest wall (local RT), 10% (n=53) received additional axillary radiotherapy on level I and II (local RT + level I-II) and 15% (n=78) of the patients received local radiotherapy with axillary irradiation including levels III and IV (local RT + level I-IV) (Table 1). ALND (n=84) was performed in 10% (n=40) of the patients in the local RT group and in 56% (n=44) of the locoregional RT group (Table 1). Patients in the ALND group reported significantly lower arm function compared to the non-ALND group (Figure 1A-B). For patients who underwent ALND and local RT, arm symptoms were significant worse at baseline and 3 months compared to non-ALND patients who received local RT and axillary (level I-II or level I-IV) irradiation (MD -15.2, p=0.00 and - 13.4, p=0.00) (Figure 1C). Overall QoL scores were similar.