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. Author manuscript; available in PMC: 2017 Oct 19.
Published in final edited form as: Lancet Oncol. 2017 Mar 2;18(3):e143–e152. doi: 10.1016/S1470-2045(17)30074-8

Table 1.

Comparison of RECIST 1.1 and iRECIST

RECIST 1.1 iRECIST
Definitions of measurable and non-measurable disease; numbers and site of target disease Measurable lesions are ≥10 mm in diameter (≥15 mm for nodal lesions); maximum of five lesions (two per organ); all other disease is considered non-target (must be ≥10 mm in short axis for nodal disease) No change from RECIST 1.1; however, new lesions are assessed as per RECIST 1.1 but are recorded separately on the case report form (but not included in the sum of lesions for target lesions identified at baseline)
Complete response, partial response, or stable disease Cannot have met criteria for progression before complete response, partial response, or stable disease Can have had iUPD (one or more instances), but not iCPD, before iCR, iPR, or iSD
Confirmation of complete response or partial response Only required for non-randomised trials As per RECIST 1.1
Confirmation of stable disease Not required As per RECIST 1.1
New lesions Result in progression; recorded but not measured Results in iUPD but iCPD is only assigned on the basis of this category if at next assessment additional new lesions appear or an increase in size of new lesions is seen (≥5 mm for sum of new lesion target or any increase in new lesion non-target); the appearance of new lesions when none have previously been recorded, can also confirm iCPD
Independent blinded review and central collection of scans Recommended in some circumstances—eg, in some trials with progression-based endpoints planned for marketing approval Collection of scans (but not independent review) recommended for all trials
Confirmation of progression Not required (unless equivocal) Required
Consideration of clinical status Not included in assessment Clinical stability is considered when deciding whether treatment is continued after iUPD

“i” indicates immune responses assigned using iRECIST. RECIST=Response Evaluation Criteria in Solid Tumours. iUPD=unconfirmed progression. iCPD=confirmed progression. iCR=complete response. iPR=partial response. iSD=stable disease.