RECIST (Response Evaluation Criteria In Solid Tumors) is a set of published criteria that define when cancer patients improve (“respond”), stay the same (“stable”) or worsen (“progression”) during treatments.
The original criteria were published in February 2000 by an international collaboration including the European Organization for Research and Treatment of Cancer (EORTC), National Cancer Institute (NCI) of the United States and the National Cancer Institute of Canada Clinical Trials Group.
RECIST 1.1, published in January 2009, is an update to the original criteria. The EORTC presentation can be found here. Today, the majority of clinical trials evaluating cancer treatments for objective response in solid tumors are using RECIST to assist with monitoring for risk versus benefit.
Cancer trials are increasingly complex, involving dozens or even hundreds of investigators from centers around the world. While the RECIST rules are highly dependent upon measurement of tumor size, different clinicians may vary greatly in their methods of performing these measurements. Consistency in following the imaging requirements and rules is even more challenging. When investigators vary in how they follow RECIST as a trial endpoint, the study results may be placed in jeopardy by significant levels of variability. This is why the EORTC developed the RECIST 1.1 Questions and Clarification document. The EORTC also developed a standard CRFs and follow up CRF.
However, currently RECIST criteria are a voluntary, international standard, based on a simplification of former methods (WHO, ECOG) and based on measurable disease, i.e., the presence of at least one measurable lesion.
RECIST criteria offer a simplified, conservative, extraction of imaging data for wide application in clinical trials. They presume that linear measures are an adequate substitute for 2-D methods and registers four response categories:
- CR (complete response) = disappearance of all target lesions
- PR (partial response) = 30% decrease in the sum of the longest diameter of target lesions
- PD (progressive disease) = 20% increase in the sum of the longest diameter of target lesions
- SD (stable disease) = small changes that do not meet above criteria
Plans call for improving on RECIST methodology by developing and validating clinical trial-acceptable methods and standards to incorporate:
- volumetric (3D) anatomical imaging
- dynamic contrast imaging
- functional (molecular) imaging
If successful, the use of medical image data as a surrogate endpoint in clinical trials could lead to:
- Smaller clinical trials with fewer patients
- Earlier go/no decisions on drug compounds
- Faster regulatory approval for new drugs
- Earlier use in clinical care