RECIST 1.1 response calculator
Enter the sum of diameters at baseline and on the current study (and the nadir, if the current sum is not the smallest). The calculator applies the 30% / 20% + 5 mm rules, combines target, non-target and new-lesion status into the overall response, and writes the sentence you paste into the report. The selection rules and the full response tables are reproduced below.
Choosing target lesions
| Rule | RECIST 1.1 |
|---|---|
| Measurable lesion | Longest diameter ≥ 10 mm on CT with slice thickness ≤ 5 mm (≥ 2× slice thickness otherwise); ≥ 10 mm calliper measurement on clinical exam; ≥ 20 mm on chest X-ray. |
| Lymph nodes | Measured by SHORT axis. ≥ 15 mm = measurable, may be a target; 10 to < 15 mm = pathological but non-target; < 10 mm = normal, not a lesion. A target node keeps contributing its actual short axis to the sum even once it falls below 10 mm. |
| How many | Up to 5 target lesions in total, no more than 2 per organ, chosen for size and reproducible measurement, representative of all involved organs. |
| Sum of diameters | Longest diameters of non-nodal targets plus short axes of nodal targets. The baseline sum is the PR reference; the smallest sum on study (which may be the baseline) is the nadir and the PD reference. |
| Not measurable | Bone lesions without a soft-tissue component, leptomeningeal disease, ascites, effusions, lymphangitic spread, cystic or necrotic lesions, previously irradiated lesions, and anything below the size threshold are non-target only. |
Target lesion response
| Code | Response | Rule |
|---|---|---|
| CR | Complete response | Disappearance of all target lesions, and every pathological lymph node (target or non-target) reduced to < 10 mm short axis. |
| PD | Progressive disease | ≥ 20% increase in the sum relative to the nadir (the smallest sum on study, including baseline) AND an absolute increase of ≥ 5 mm. The appearance of one or more new lesions is also PD. |
| PR | Partial response | ≥ 30% decrease in the sum relative to the baseline sum. |
| SD | Stable disease | Neither sufficient shrinkage for PR nor sufficient increase for PD. |
Order of precedence: CR, then PD (assessed against the nadir), then PR (assessed against baseline), then SD. A sum that has fallen 40% from baseline but risen 50% from its nadir is PD, not PR. Target lesions that disappeared and then reappear are PD whatever their size. A target node that shrinks below 10 mm keeps its actual short axis in the sum, so a complete response can have a non-zero sum — hence the checkbox above.
Overall response
For patients with target lesions at baseline (Eisenhauer et al., Table 3). Non-target disease can only hold the overall response at PR or SD, or push it to PD; it never improves it.
| Target | Non-target | New lesions | Overall |
|---|---|---|---|
| CR | CR | No | CR |
| CR | Non-CR/non-PD | No | PR |
| CR | Not evaluated | No | PR |
| PR | Non-PD or not evaluated | No | PR |
| SD | Non-PD or not evaluated | No | SD |
| PD | Any | Yes or No | PD |
| Any | PD | Yes or No | PD |
| Any | Any | Yes | PD |
Non-target progression must be unequivocal: a modest increase in one or two non-target lesions is not PD when target disease is stable or responding. Best overall response in trials additionally requires a confirmation scan for CR and PR and a minimum duration for SD, which this page does not model.
What RECIST 1.1 is not for
- Immunotherapy. Immune-related pseudoprogression is scored PD by RECIST 1.1. Trials of checkpoint inhibitors use iRECIST, which introduces unconfirmed PD (iUPD) and a confirmation scan.
- Bone-only disease. Blastic and lytic lesions without a soft-tissue component ≥ 10 mm are non-measurable; RECIST 1.1 cannot give a target response. The MD Anderson criteria or PERCIST are used instead.
- Lesions below threshold. A sum built from lesions < 10 mm (or nodes < 15 mm short axis) is not a RECIST sum; small lesions are non-target and are followed qualitatively.
- Other systems. Lymphoma (Lugano), hepatocellular carcinoma (mRECIST), glioma (RANO), mesothelioma (modified RECIST) and GIST (Choi) each have their own criteria; do not report RECIST 1.1 on them without being asked.
Related
- Nodule volume doubling time — growth over time rather than response
- LI-RADS calculator — HCC is reported with LI-RADS and mRECIST, not RECIST 1.1
- All radiology calculators
MyRadAgent drafts the full report - and applies this guideline automatically, with the category and follow-up in the impression. Free trial runs in the browser: 100 reports over 14 days, no card, no IT ticket.
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