ESTRO 38 Abstract book

S1163 ESTRO 38

EP-2103 Development of a personalized, interactive patient decision aid for participation in clinical trials C. Offermann-Wulms 1 , C. Roumen 1 , A. Ankolekar 1 , J. Coenen 1 , I. Nijsten 1 , R. Fijten 1 , D. De Ruysscher 1 1 Maastro Clinic, Department of Radiotherapy, Maastricht, The Netherlands Purpose or Objective Performing clinical trials is a crucial step towards changing standard clinical practice. Lack of statistical power is one of the major problems hampering clinical trials, thus ensuring that appropriate inclusion in trials takes place is crucial. However, cancer patients often do not make informed decisions regarding clinical trial participation. This is due to misconceptions and wrong beliefs that trial participants do not receive the best possible care, and due to the fact, that written or oral information about clinical trials is often incomplete, complex, unclear and confusing. Therefore, patient-centered approaches in clinical trials call for support in the decision-making process, guiding patients to clarify their preferences and values, and helping patients make a well-informed decision about participation. To this end, we developed a web-based patient decision aid for trial participation (tDAT). Material and Methods The tDAT was developed between April 2017 and April 2018 according to the international patient decision aid standard (IPDAS) guidelines. First, we identified views on decisional needs for trial participation of stakeholders (e.g. trial experienced patients, trial assistants, physicians) and verified these needs in scientific literature and by interviewing patients who were already participating in a clinical trial. Based on this evidence, a prototype was developed, which was subsequently tested by stakeholders using semi-structured interviews. This review by the stakeholders led to a redraft and redesign. Results The resulting tDAT displayed information about trial participation in an interactive manner and without medical jargon. The general information on the definitions of clinical trials are given by using animations, videos and written text in which the trial participation process is explained. Additionally, a questionnaire is included that allows patients to test their gained knowledge. This is followed by multiple comparisons to determine what matters to them based on their personal preferences. At the end, the patient receives an overview of their preferences which they can then discuss with the trial assistant and/or MD in order to make a founded and better–informed decision.

Conclusion We have developed a tDAT that will enable us to test our hypothesis that well-informed patients are more likely to participate in a trial and less likely to drop-out of a trial. In the near future, we will be conduction a trial to evaluate the quality and effectiveness of our current web- based tDAT. This will be done after stakeholders tested the feasibility of the tool. EP-2104 Audit of the dosimetric impact of weight loss in head and neck patients to assess when a re-plan is required N. Lalli 1 , S. Khan 2 , L. Hong 2 , M. Daly 2 , D. Carnell 2 , R. Mendes 2 , A. Thompson 2 1 University College London Hospital NHS Trust, Radiotherapy Physics, London, United Kingdom ; 2 University College London Hospital NHS Trust, Radiotherapy, London, United Kingdom Purpose or Objective Anatomical changes including weight loss can cause dosimetric changes over a course of VMAT radiotherapy for head and neck cancer, affecting target volume coverage or organ at risk dose. Adaptive re-planning can be used to mitigate these effects; however doing this can require additional time and resources. Repeat planning CTs can contribute concomitant radiation dose. Calculating the planned dose using on-treatment CBCT images helps quantify the dosimetric changes to OARs, facilitating decision-making when faced with weight loss during treatment. At UCLH, when patient separation loss is observed on weekly CBCTs, a request is sent to the physics team to implement a dosimetric assessment. The planned patient external contour is amended to reflect the recent CBCT. The plan is re-calculated to document the changes in target coverage and OAR doses, and is reviewed by the clinician to determine if action is required. The purpose of this study was to audit the existing process and determine whether it could be streamlined within our department. Being able to identify patients where weight loss can have an undesired dosimetric impact and when and to take effective action was the endpoint of this study.