Response evaluation criteria in solid tumors (RECIST) is a set of published rules that define when tumors in cancer patients improve ("respond"), stay the same ("stabilize"), or worsen ("progress") during treatment.
Today, the majority of clinical trials evaluating cancer treatments for objective response in solid tumors use RECIST.
Many oncologists in their daily clinical practice follow their patients' malignant disease by means of repeated imaging studies and make decisions about continuing therapy on the basis of both objective and symptomatic criteria.
It is not intended that these RECIST guidelines play a role in that decision making, except if determined appropriate by the treating oncologist.
In the mid-1990s, an International Working Party was created to simplify and standardize response criteria; it then published RECIST in 2000.