Table 1.

Response criteria

	Modified RECIST 1.1[13]	Modified EORTC [12]	ICDS [14]
CR	Disappearance of all target lesions; all target lymph nodes are < 10 mm in the short axis	Complete resolution of abnormal 18FDG uptake within the tumor volume of all target lesions to a level that is indistinguishable from surrounding normal tissue	Disappearance of all disease
PR	At least a 30% decrease in SLD using baseline SLD as a reference	Reduction of the sum of the SUVmax by ≥ 15–25% after 1 cycle and a decrease of ≥ 25% compared with baseline after > 1 treatment cycle	A decrease in size (%Δ Choi SLD) ≥ 10% or an increase in CT density > 15% compared with baseline, no new lesions, and no obvious progression of nonmeasurable disease
SD	Neither sufficient shrinkage of target lesions to qualify for PR nor sufficient increase to qualify for PD, taking as reference the nadir SLD	%ΔΣ SUVmax increased by < 25% or decreased by < 15% compared with baseline and no visible extent of 18FDG tumor uptake (> 20% in the longest dimension)	Does not meet the criteria for CR, PR, or PD; no symptomatic deterioration attributed to tumor progression
PD	At least a 20% increase in the SLD of target lesions, taking as reference the nadir SLD; in addition to the relative increase of 20% in SLD, the SLD must also demonstrate an absolute increase of ≥ 5 mm	%ΔΣ SUVmax increased by ≥ 25% compared with baseline scan, visible increase in the extent of 18FDG uptake (> 20% in the longest dimension) or the appearance of new 18FDG uptake in metastatic lesions	An increase in unidimensional tumor size (Choi SLD) ≥ 10% and does not meet the criteria for PR using CT density; any new lesions identified by CT/MRI; new intratumoral nodules or increase in the size of existing intratumoral nodules
UE	A target lesion present at baseline that subsequently became UE	18FDG-PET exam was unavailable or deemed UE;a response will be UE unless unequivocal PD is determined on the basis of the evaluable target lesion	The CT/MRI exam is unavailable or deemed UE; if a target lesion is deemed UE by density and size measurement and the rules for PD do not apply, a response of CR, PR, or SD cannot be assigned for the time point and the response will be UE

RECIST Response Evaluation Criteria in Solid Tumors, EORTC European Organisation for Research and Treatment of Cancer, ICDS inverse Choi density/size, CR complete response, ¹⁸FDG-PET 2-deoxy-2- [¹⁸F]-fluorodeoxyglucose positron emission tomography, PR partial response, SLD sum of longest diameter, SUV_max maximum standardized uptake value, SD stable disease, PD progressive disease CT computed tomography, MRI magnetic resonance imaging, UE unevaluable

^aThe UE rate for this study was essentially 0