As a surrogate marker of treatment efficacy, RECIST has been tested through many clinical trials as well as real-life practice and found to correlate well with the gold standard of overall survival. By assessing the change in tumor burden after therapy through unidimensional measurements, RECIST provides not only a reliable indicator of response to treatment, but also a standard that is a sort of common language to all clinical trials for solid tumors.

Indeed, in recent clinical trials, correlation between RECIST findings and outcomes from early data has been lacking, reinforcing the notion that other imaging criteria should be considered to assess tumor response.

Here we explore such imaging criteria “beyond RECIST.”