ESTRO 2020 Abstract book

S80 ESTRO 2020

the steps that need to be taken to move rapid learning into the clinic.

approach. In addition, important aspects such as the sensitivity and specificity of control charts, as well as the impact and management of measurement uncertainty will be discussed.

Symposium: Radiotherapy: it´s all about the heart

SP-0153 Challenges in treating IMC: An RTT perspective N. Roberts 1 , S. Wickers 2 , D. Ledsom 3 1 leeds Cancer Centre, Radiotherapy, Leeds, United Kingdom ; 2 university College Hopsital, Radiotherapy, London, United Kingdom ; 3 clatterbridge Cancer Centre, Radiotherapy, Liverpool, United Kingdom Abstract text Background: In 2016 the UK consensus guidelines for post- operative breast cancer radiotherapy (RT) were published (1). A consensus was reached on treatment of the internal mammary nodal chain (IMC) based on the most up to date evidence available. The strength of the recommendation varies when considering whether to treat different 'at risk' patient populations within the early breast cancer cohort, hence the word ‘consider' is used in relation to patients with high and low nodal disease burden. Evidence: If outcome measures of all the recent RCTs are combined for ≈11,000 women with median FU of 9.1 years then statistically significant outcomes are reached for: any recurrence, breast cancer specific mortality and overall survival (2). The lack of clarity in consensus reflects the current evidence base with patient disease characteristics under investigation differing somewhat between these studies, but the majority of patients randomised had low volume nodal disease (pN1-3) (3)(4)(5). Absolute mortality benefit was greatest in patients with a higher nodal burden (N4+). Key to this evidence update is the data that shows the more recent RT techniques are far better at sparing organs at risk (OAR) and achieving superior target volume coverage. This is reflected in non-breast cancer mortality which shows no significant difference between patients having IMC and non-IMC RT, a reversal from the older studies that attributed a higher death rate to IMC treatments to excess heart and lung doses (2). The landmark studies into IMC RT have evoked new consideration of treatment for patients where this anatomical region has previously been omitted from the target volume in UK practice. Developing an IMC technique: Traditional RT technique delivery for patients in this disease cohort would include tangential fields to the breast/chest wall with a direct anterior field to the level 4 nodes (SCF). Including the IMC into the target volume poses additional challenges such as; how and what to delineate, how to meet dose constraints for OARs and the potential for increased low dose bath when employing advanced techniques such as VMAT. Given the differences in referring population & radiotherapy planning and delivery equipment, the development and implementation of IMC RT has taken different paths for many cancer centres across the UK. The Leeds Cancer Centre (LCC), University College Hospital London (UCLH) and Clatterbridge Cancer Centre (CCC) represent a diverse referring population and mix of radiotherapy planning and delivery solutions. All have experienced challenges in the development of IMC RT in breast cancer since the consensus guidelines were published. Challenges not only in developing the technique but also in selecting the patient groups that will benefit most whilst ensuring additional resource requirements are used appropriately across the health service. Figure 1 highlights key areas of development that each centre has tackled in implementing IMC RT. At each centre the RTT has been pivotal in this development and case studies from these centres help to illustrate how these challenges have been met. References: (1) Royal College of Radiologists, Faculty of Clinical Oncology on behalf of the core group, 2016, Postoperative radiotherapy for breast cancer: UK consensus statements, retrieved from:

SP-0152 “Rapid learning”: Using real world data to improve clinical practice G. Price 1 1 Manchester Cancer Research Centre, Radiation Related Research Department 58 The Christie NHS Foundation Trust, Manchester, United Kingdom Abstract text Real world data – the information routinely collected about patients over their care pathway – offers an opportunity to provide evidence where Randomized Controlled Trials (RCTs) are not practical. There is an unmet need for such approaches in radiotherapy where many changes to practice are not suited to RCTs meaning there is often only limited assessment of their impact on clinical outcomes. The quantity and quality of data collected in modern radiotherapy mean it is ideally suited to such analyses. Furthermore, if real world data can be used to evaluate the effect of changes to radiotherapy practice, it opens the door to the use of iterative quality improvement techniques to optimize treatments. In this approach, often called rapid learning, a change to practice is made, its effect evaluated, and this information used to refine the next change before testing its effect again. It has the potential to transform the way in which new technologies and protocols are introduced into the radiotherapy clinic. It is not yet, however, in widespread use. This lecture will explore the promise of rapid learning and consider some of the challenges to its routine implementation. It will discuss the advantages and disadvantages of working with real world data in different ways, comparing the use of selective ‘simple trials’ and Trials within Cohorts (TwiCs) to before-after and time- series analyses. As well as examining the trade-offs in the evidence produced by different methodologies we will discuss their practicalities, including consideration of different patient consent models. Finally we will use a case study of heart sparing in lung radiotherapy to discuss