TABLE 1.

Summary of Major Changes in Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 Compared With RECIST 1.0

RECIST Guideline	RECIST 1.1	RECIST 1.0
No. of target lesions	Up to 2 per organ; up to 5 in total	Up to 5 per organ; up to 10 in total
Assessment of lymph nodes	Short-axis measurements should be used and recorded; ≥ 15 mm, target lesions; ≥ 10 mm but < 15 mm, nontarget lesions; < 10 mm, nonpathological	No clear guideline provided
Clarification of disease progression	20% increase in the sum of target lesions and 5-mm absolute increase are required	20% increase in the sum of target lesions (no minimum absolute size increase is required)
FDG PET scan	Included only in the detection of new lesionsa	Not included

^aNew lesions on the basis of FDG PET can be identified according to the following algorithm [2]: a negative FDG PET at baseline with a positive FDG PET at follow-up is a sign of progressive disease based on a new lesion. For no FDG PET at baseline and a positive FDG PET at follow-up, if the positive FDG PET at follow-up corresponds to a new site of disease confirmed by CT, this is progressive disease. If the positive FDG PET at follow-up is not confirmed as a new site of disease on CT, additional follow-up CT scans are needed to determine whether there is truly progression occurring at that site. If the positive FDG PET at follow-up corresponds to a preexisting site of disease on CT that is not progressing on the basis of the anatomic images, this is not progressive disease.