RECIST Calculator
The RECIST 1.1 criteria are a widely used method of assessing radiological response to cancer therapy in solid tumours.
First published in 2000 the criteria aim to standardise tumour response assessment, which is particularly important in clinical trials(1). The criteria were updated in 2009(2)
The preferred imaging modality is CT with IV contrast using 5mm thick slices. In some instances, xray or MRI may be used but it is important to use the same imaging modality at each assessment.
Baseline imaging should be performed less than 4 weeks before treatment begins.
At baseline measurable and non-measurable disease lesions are recorded and used as the comparator in future assessments.
Measurable disease is defined as the presence of at least 1 measurable lesion (see details below). Up to 5 measurable lesions are selected as target lesions for ongoing assessment.
Target lesion assessment
A
solid tumour target lesion must be
≥10mm in long axis diameter at baseline.
A
lymph node lesion must be
≥15mm in short axis diameter at baseline.
Up to 5 target lesions meeting the above criteria that can be reproducibly measured should be selected at baseline.
A maximum of 2 lesions per organ are allowed.
Bone lesions can be included if the soft tissue component is ≥10mm in long axis diameter at baseline. Lytic and mixed lytic/blastic lesions are allowed but entirely blastic bone lesions are not allowed.
Lesions that have been previously irradiated or subjected to other loco-regional therapy are not allowed.
Non-target lesion assessment
These are lesions that cannot be reproducibly measured or don’t meet the criteria above for measurable disease.
Can include malignant pleural/pericardial effusions, ascites, lymph nodes or solid tumour lesions not meeting the criteria above, lymphangitic lung or skin lesions, inflammatory breast disease or bone lesions without soft tissue component.
Response categories for target lesions
Complete response (CR)
Disappearance of all target lesions.
All pathological lymph nodes (whether target or non-target lesions) should have short axis diameter of <10mm.
Partial response (PR)
≥30% reduction in the sum diameter of target lesions
compared to baseline assessment.
Stable disease (SD)
Neither sufficient decrease to qualify for PR nor sufficient increase to qualify for PD.
Progressive disease (PD)
≥20% increase in the sum diameter of target lesions
compared to smallest (nadir) measurement value during study. In addition the sum increase must be ≥5mm.
Response categories for non-target lesions
Complete response (CR)
Disappearance of all non-target lesions. All lymph nodes should have short axis diameter of <10mm.
Non-CR/Non-PD
One or more non-target lesions remain present.
Progressive disease (PD)
Unequivocal substantial worsening in one or more non-target lesions or new lesions, even in the presence of SD or PR in measurable disease. A modest increase in non-target lesions is not sufficient to call progression of non-target disease. Examples include increase of a malignant pleural effusion from trace to large or increase in lymphangitic disease from localised to widespread.
Overall time-point response
In patients with both measurable and non-measurable disease at baseline, overall response is as per the table below.
In patients with measurable or non-measurable disease only at baseline, overall response is as per target and non-target lesion assessment above respectively.
Further guidance notes
If a target lesion disappears, it should be recorded as 0mm in size. If it becomes too small for accurate measurement but remains visible then it should be assigned a default value of 5mm.
If a lesion fragments, the individual lesion diameters should be added together to get the target lesion sum.
If lesions coalesce, a plane between them may remain allowing measurement of each individual lesion. If lesions have truly coalesced and are inseparable the longest diameter should be measured for the merged lesion and recorded once in the sum of target lesions.
References:
- Therasse P, Arbuck SG, Eisenhauer EA, et al. New guidelines to evaluate the response to treatment in solid tumors. European Organization for Research and Treatment of Cancer, National Cancer Institute of the United States, National Cancer Institute of Canada. J Natl Cancer Inst. 2000;92(3):205-216. doi:10.1093/jnci/92.3.205
- Eisenhauer EA, Therasse P, Bogaerts J, et al. New response evaluation criteria in solid tumours: revised RECIST guideline (version 1.1). Eur J Cancer. 2009;45(2):228-247. doi:10.1016/j.ejca.2008.10.026
