Table 5.

Revised Cheson Criteria for Malignant Lymphoma

Response	Definition	Nodal masses	Spleen, Liver	Bone marrow
CR	Disappearance of all evidence of disease	• FDG-avid or PET positive prior to therapy; mass of any size permitted if PET negative • Variably FDG-avid or PET negative; regression to normal size on CT	Not palpable, nodules disappeared	Infiltrate cleared on repeat biopsy; if indeterminate by morphology, immunohistochemistry should be negative
PR	Regression of measurable disease and no new sites	≥ 50 % decrease in SPD of up to 6 largest dominant masses; no increase in size of other nodes; • FDG-avid or PET positive prior to therapy; one or more PET positive at previously involved site • Variably FDG-avid or PET negative; regression on CT	≥ 50 % decrease in SPD of nodules (for single nodule in greatest transverse diameter); no increase in size of liver or spleen	Irrelevant if positive prior to therapy; cell type should be specified
PD or relapsed disease	Any new lesion or increase by ≥ 50 % of previously involved sites from nadir	Appearance of a new lesion(s) > 1.5 cm in any axis, ≥ 50 % increase in SPD of more than one node, or ≥ 50 % increase in longest diameter of a previously identified node > 1 cm in short axis; lesions PET positive if FDG-avid lymphoma or PET positive before therapy	> 50 % increase from nadir in the SPD of any previous lesions	New or recurrent involvement
SD	Not meet above criteria	• FDG-avid or PET positive prior to therapy; PET positive at prior sites of disease and no new sites on CT or PET • Variably FDG-avid or PET negative; no change in size of previous lesions on CT

CR complete remission, FDG fluorodeoxyglucose, PD progressive disease, PET positron emission tomography, PR partial remission, SD stable disease, SPD sum of the product of the diameters