Improving radiotherapy quality assurance in clinical trials: assessment of target volume delineation of the pre-accrual benchmark case

Abstract

As the complexity of radiotherapy (RT) trials increases, issues surrounding target volume delineation will become more important. Some form of outlining assessment prior to trial entry is increasingly being mandated in UK RT trials. This document produced by the Outlining and Imaging Subgroup (OISG) of the National Cancer Research Institute will address methods to reduce interobserver variation in clinical trials and how to conduct an assessment of outlining through a pre-accrual benchmark case. We review currently available methods of describing the variation and identify areas where further work is needed. The OISG would encourage ongoing discussion with chief investigators in order to provide advice on individual aspects of benchmark case assessment for current and future trials.The importance of quality assurance (QA) in radiotherapy (RT) trials has been highlighted by recent publications showing that protocol deviations can negatively impact on survival in head and neck and pancreatic cancer trials [1,2]. These studies have focused predominantly on planning rather

Conformity analysis to demonstrate reproducibility of target volumes for Margin-Intense Stereotactic Radiotherapy for borderline-resectable pancreatic cancer

“…Errors in target volume delineation tend to be larger than other geometric errors in radiotherapy planning, and also cause a systematic error, not only for a specific patient but potentially for all patients treated by a given clinician or centre [20]. In theory the GTV should be a factual entity defined by all observers in the same way, but despite this significant inter-observer variability has been recorded in contours of tumours and organs at risk [21] and in our study we have observed a large variation even among a small group of experienced clinicians.…”

“…In a study of chemoradiotherapy for locally-advanced pancreatic cancer, protocol deviations such as unnecessarily large target volumes correlated with risk of significant toxicity [32] while in a large study of adjuvant chemoradiotherapy after resection of pancreatic adenocarcinoma, failure to adhere to the radiotherapy protocol was associated with decreased overall survival [33]. Therefore, it is recommended that radiotherapy trials are supported by a prospective and comprehensive quality assurance programme [20]. We have shown that pancreatic GTV delineation remains difficult, which reinforces the importance of pre-treatment central review of target structures to ensure consistency and quality across recruiting centres.…”

Prospective review of radiotherapy trials through implementation of standardized multicentre workflow and IT infrastructure

“…9 While this approach is associated with improved protocol compliance, 3 to ensure the ongoing quality of the RT delivery within the trial, depending on the complexity of the RT, it should be complemented by some form of on-trial assessment [individual case review (ICR)]. 10 The UK National Radiotherapy Trials Quality Assurance (RTTQA) group operates from four sites, ours being one of the host sites. Much of the ICR for trials supported by this group has been retrospective, in keeping with many other international trials.…”

Is pre-trial quality assurance necessary? Experiences of the CONVERT Phase III randomized trial for good performance status patients with limited-stage small-cell lung cancer

“…In a recent review, the RTTQA group discussed methods of reducing interobserver variation in outlining and the use of a pre-trial benchmark case to assess the outlining quality. 9 …”