EU issues new criteria for measuring tumor size, progression to ease clinical trials
A formal revision of the Response Evaluation Criteria in Solid Tumors (RECIST), which is used by clinicians to measure tumor size and response to treatment, was published Tuesday in a special issue of the European Journal of Cancer (EJC), the journal of the European Cancer Organization.

RECIST (Response Evaluation Criteria in Solid Tumors), first published in 2000, are used by investigators in phase II and phase III clinical trials of new anti-cancer drugs as a way of measuring the efficacy of the treatment. Tumor shrinkage and time to the development of disease progression are both important endpoints in trials, and, increasingly in recent years, trials have been using time to progression (or progression-free survival) as their main endpoint on which to base conclusions about the efficacy of a drug.

The new RECIST—RECIST 1.1 to distinguish them from the original RECIST—answer some of the questions and issues that have arisen since 2000 as a result of changing methodologies and available treatments.

Jaap Verweij, MD, from the Erasmus University Medical Centre in the Netherlands, the EJC’s clinical oncology editor and a co-editor of the special issue on RECIST, said that “RECIST 1.1 describes a standard approach to solid tumor measurement and definitions for objective assessment of change in tumor size for use in adult clinical trials.”

Changes in RECIST 1.1 that will standardize the assessment of tumor burden in clinical trials include:
  • A reduction in the number of lesions to be assessed for response from a maximum of ten to five, and from five to a maximum of two per organ;
  • New guidance on making robust measurements of lymph node involvement;
  • Confirmation of response is required for trials with objective response as a primary endpoint, but is no longer required for randomized studies, since the control arm of the studies provides appropriate means for interpreting the experimental arm;
  • The definition of disease progression has been refined so that it not only includes a 20 percent increase in the size of the lesion, but also a 5 mm absolute increase as well, so that changes of just a few mms in very small tumors;
  • Guidance on imaging, including its use in the detection of new lesions and the interpretation of FDG-PET scan assessment.

EJC Co-editor Elizabeth Eisenhauer, MD from the National Cancer Institute of Cancer in Ontario, Canada, stressed that the recommendations are evidence-based: “They are grounded in the literature and where such information didn’t exist – as was the case in some areas – we set about generating the evidence to guide and support the changes.”

The database consisted of more than 6,500 patients with more than 18,000 target lesions, and was used to investigate the impact of a variety of questions, such as the number of lesions needing to be measured.

“Our consequent recommendation that the number of lesions measured should be reduced from ten to five will have a big implication for the workload in clinical trials and we found that it will have no impact on described study outcomes,” Eisenhauer said. “This change can be made without any loss of information.”