ESTRO 38 Abstract book

S251 ESTRO 38

planning and delivery of radiotherapy. Intensity modulated radiotherapy and volumetric modulated arc therapy are now commonly implemented for clinical use. Combining the concept of hypofractionated radiotherapy and the use of image guided radiotherapy, these advanced highly precise treatment techniques can be utilised to deliver ablative doses of radiation to tumours while sparing the surrounding normal tissues as commonly known as stereotactic radiotherapy. Hypofractionated high dose per fraction requires greater clinical, dosimetric and geometric accuracy. Interval between fractions and gaps in radiotherapy schedules can be critical in maintaining the overall treatment outcome. With the introduction of advanced radiotherapy technology, this has increased the complexity of the treatment process resulting in a shift in types and levels of responsibility taken between clinicians, physicists and radiation therapists (RTTs). It provides an opportunity for RTTs to extend their roles and scopes of practice. RTTs should understand the scientific basis and clinical rationale of extreme-hypofractionated radiotherapy and the importance of accurate delivery to tackle both systematic and random errors in this setting. Development of a comprehensive training and competency assessments is an essential aspect of introducing a culture of accuracy in the advanced hypofractionated radiotherapy delivery, irrespective of resource constraints. Before implementing advanced hypofractionated radiotherapy, an institution should review its resources and working practices to define the level of accuracy that is realistically achievable. The number of patients who can be treated accurately within a given time frame and the level of complexity that can be safely implemented into daily practice should be considered. All of these will be discussed in this presentation with the aim to explore the perceived impact of extreme-hypofractionated radiotherapy in operating a radiotherapy department with a RTT’s perspective. SP-0489 This house believes that the EBRT is the best technique C. Coles 1 1 University of Cambridge, Oncology, Cambridge, United Kingdom radiotherapy: Is non-inferior to whole breast radiotherapy with excellent local control rates, DFS and OS and is the only technique whereby patients have reported better breast appearance and less late side effects 1 . Can be given in just 5 daily outpatient treatments as illustrated by the UK FAST Forward trial 3-year toxicity results and is non-invasive. Does not require specialist training and is therefore far more accessible for patients. Uses existing standard equipment and this simple technique can be implemented in all radiotherapy centres worldwide with no/minimal additional resources. 1. Coles CE, Griffin CL, Kirby AM, Titley J, Agrawal RK, Alhasso A, Bhattacharya IS, Brunt AM, Ciurlionis L, Chan C, Donovan EM, Emson MA, Harnett AN, Haviland JS, Hopwood P, Jefford ML, Kaggwa R, Sawyer EJ, Syndikus I, Tsang YM, Wheatley DA, Wilcox M, Yarnold JR, Bliss JM; IMPORT Trialists. Partial-breast radiotherapy after breast conservation surgery for patients with early breast cancer (UK IMPORT LOW trial): 5-year results from a multicentre, randomised, controlled , phase 2, non-inferiority trial. Lancet 2017 Sep 9;390(10099):1048-1060. Abstract text External beam partial breast Debate: Which is the best technique for the delivery of APBI?

SP-0490 This house believes that the multicatheter brachytherapy is the best technique V. Strnad 1 1 University Hospital Erlangen, Dept. Radiation Oncology, Erlangen, Germany Abstract text Purpose: To analyze the facts about adjuvant interstitial brachytherapy-based Accelerated Partial Breast Irradiation (APBI) after breast conserving surgery in terms of clinical experience, quality assurance and clinical results. Methods and Materials: The multicatheter brachytherapy is unique among the different techniques of APBI for a lot of reasons. The author analyses in a matter-of-fact and detailed fashion the facts in this context: 1. High Quality assurance and reproducibility; 2. Technique with the longest experience among all APBI techniques; 3. Level 1 evidence - excellent efficacy - the same whole breast irradiation (WBI); 4. Level 1 evidence - lower incidence of late side effects in comparison to WBI; 5. Level 1 evidence – better Quality of Life (QoL) in comparison to WBI; 6. In comparison to APBI using different external beam therapy techniques the multicatheter brachytherapy reduces in majority of anatomic scenarios significant doses to all relevant organs The published data imposingly demonstrate the very long experience of brachytherapy as a technique for APBI. The first Phase II APBI-trials were started more than 20 years ago and over the same time the basic rules of image- guided multicatheter brachytherapy techniques have been developed and guidelines published. Long-term follow-up outcomes in two Phase 3 trials show that APBI using multicatheter brachytherapy yields equivalent local control, disease-free survival, and overall survival after breast-conserving treatment compared with conventional whole-breast irradiation. In large multicentre GEC-ESTRO trial after median follow-up of 6.6 years exceptionally low overall recurrence about 1% at 5 years in both treatment arms has been reported (p=0.4). Analogous also 5-year disease-free survival was 94,5%) with whole-breast irradiation and 95% with APBI (p=0.8) and breast cancer- related mortality did, hitherto, not differ between groups (four events vs four events; p=0.8). Furthermore 5-year toxicity profiles and cosmetic results were similar in patients treated with breast-conserving surgery followed by either APBI with interstitial brachytherapy or conventional whole-breast irradiation, with significantly fewer grade 2-3 late skin side-effects after APBI with interstitial brachytherapy. APBI with multicatheter brachytherapy is also associated in general with equal quality of life (QoL) compared with whole-breast irradiation, but in details moderate, statistically and clinical significant difference of QoL between the groups was found in the breast symptoms scale in favour for brachytherapy based APBI. In addition to it the published dosimetric comparisons of different APBI techniques described, that the multicatheter brachytherapy in comparison to external beam based APBI-techniques reduces in majority of anatomic scenarios significant the mean doses to all relevant organs at risk and in consequence the multicatheter-based APBI is able to reduce significant as well deterministic as the stochastic late side effects in all surrounding organ at risk as heart and lung. Conclusions Summarizing the facts available to date it is obvious that APBI using brachytherapy techniques works excellently. No other technique of APBI is supported by such robust, broad positioned and encouraging data. In addition to it comparing the dose distributions of different APBI techniques, and given the long-term experience and excellent clinical results the high adaptability, versatility, precision, quality and reproducibility of brachytherapy at risk. Results