Stepwise Development and Justification of Evidence-Based Practice for Bladder Radiotherapy

Abstract

The introduction of new technology has revolutionized the way radiotherapy is delivered for bladder cancer: developing from the use of basic conventional techniques to a high precision, personalized approach. In order to demonstrate that the new technology is beneficial to the patient and to ensure its safe implementation, there is a need to integrate clinical expertise, patient values and research evidence for the development of evidence-based practice (EBP). The purpose of this presentation is to share our experiences while developing and justifying various EBPs for bladder radiotherapy at our institution. Prior to 2002, bladder patients were treated with a standard 4-field box technique with no image guidance. Since then, a series of prospective and retrospectively studies were conducted to investigate different aspects of bladder radiotherapy, such as accurate definition of treatment volume, inter- and intrafractional bladder volumes changes and surface displacements, conformity and normal organ avoidance for dose distributions, mode and frequency of image-guidance interventions and reliability of image guidance surrogates. At each stage, the impact on geometric and dosimetric precision was quantified as evidence to substantiate the use of EBPs. Based on the finding of the research studies, the following EBPs were implemented: 1) IMRT was adopted as the standard treatment technique to replace 4-field box as it demonstrated superiority in dose conformity, 2) Image guidance was initially performed with Day 1 EPI and bony anatomy. With the introduction of CBCT in 2006, online image guidance was performed daily to improve precision, 3) Radio-opaque marker and bladder wall surface were adopted to be used as image guidance surrogate for partial bladder irradiation after assessing their reliability, 4) A novel method for deriving individualized treatment volume was developed and validated against other methods to demonstrate efficacy on treatment quality. In addition to establishing a very high level of EBP in our institution, we have shared our experiences and knowledge via 9 abstracts and 2 manuscripts at various national, international conferences and peer-reviewed journals. EBPs have been successfully developed, justified and implemented using a combination of clinical expertise and research evidence, to improve the quality of bladder radiotherapy. Currently all bladder patients at our institution are treated with daily image guidance using CBCT with soft tissue alignment, with dose delivered to an individualized clinical target volume and planning target volume using IMRT.