RECIST

Target lesions are defined as the first two lesions per organ and five lesions in total, and pathologic lymph nodes with a short axis measurement of  ≥ 15mm.

All other lesions are identified as non-target lesions, including pathologic lymph nodes with a short axis measuring 10-15mm. 

 A baseline sum of the longest diameter (LD) of all the target lesions and short axis of pathologic lymph nodes, and the presence of non-target lesions are used to evaluate the changes. 

What are the components of RECIST?

Evaluation of target lesions in response to treatment:

• Complete response (CR)- All target lesions disappear for at least one month and the short axis of all pathologic lymph nodes decreases to ≤ 10mm.
• Complete response unknown (CRU)- Complete response which is accompanied by persistent abnormalities of unknown significance on imaging.
• Partial response (PR)- There is at least a 30% decrease in baseline sum.
• Stable disease (NR/SD)- There is no significant increase or decrease in the baseline sum since the start of treatment.
• Progressive disease (PD)- There is an absolute increase of 5mm and a 20% or greater increase in the baseline sum since the start of treatment.

Evaluation of non-target lesions in response to treatment:

• Complete response (CR)- All non-target lesions resolve and tumor marker levels normalize.
• Incomplete response/stable disease (SD)- One or more non-target lesion remains, and/or the level of the tumor marker remains elevated.
• Progressive disease (PD)- There is an appearance of one or more non-target lesions, and/or there is progression of the existing non-target lesions or a general increase in tumor burden.