# iRECIST — iRECIST for immunotherapy-trial response data

> Protocol-defined patient-level response data framework for immunotherapy trials. It starts from RECIST 1.1, separates new-lesion burden, and introduces unconfirmed and confirmed progression states. It is not a validated bedside response criterion, a diagnosis of pseudoprogression or an autonomous instruction to continue or stop treatment.

**Situação:** vigente · **Órgão:** Oncologia · **Órgão emissor:** RECIST Working Group · **Versão:** 2017 guideline; RECIST Working Group clarifications current through 2026 · **Ano:** 2017

> ⚠️ Uma versão mais nova pode existir (em revisão).

## Procedência e vigência
- Família: léxico
- Tipo de lógica: flat
- Modalidade: CT, MRI
- Fonte primária: Seymour L, Bogaerts J, Perrone A, et al.. iRECIST: guidelines for response criteria for use in trials testing immunotherapeutics (2017) — https://pmc.ncbi.nlm.nih.gov/articles/PMC5648544/
- Última verificação: 2026-07-24
- Última checagem: 2026-08-12

## Lógica de decisão
Run iRECIST as a longitudinal state machine over RECIST 1.1 component data. Keep trial response assignment, clinical stability, protocol action and prognosis as separate outputs.

## Categorias

| Código | Rótulo | Critérios | Conduta | Risco | Localizador | Verificado |
| --- | --- | --- | --- | --- | --- | --- |
| iCR | Immune complete response | At this evaluable protocol timepoint, all target lesions, all non-target disease and all separately tracked new lesions have disappeared, with every lymph node below 10 mm short axis and no progression override. The longitudinal record must retain the fixed baseline target set and every prior immune-response state. | Record iCR as the trial time-point response and apply any protocol-required response confirmation and scheduled imaging. It does not independently justify stopping immunotherapy, changing dose or declaring cure; clinical management remains protocol- and patient-specific. | iCR is an imaging response state, not proof of eradication and not a universal recurrence, survival or durable-benefit probability. Its prognostic meaning depends on tumor type, therapy, assessment schedule, response durability and the trial analysis plan. | Seymour et al. 2017, PMC5648544, Table 1 (iCR and lymph-node rule), Table 2 and time-point response text; Persigehl et al. 2020, PMC6942293, section Responses to therapy. | ✓ |
| iPR | Immune partial response | The target-lesion sum has decreased by at least 30% from baseline after synthesis of target, non-target and separately tracked new-lesion compartments, without an iUPD or iCPD override. A prior unconfirmed progression does not prevent later iPR when progression is not confirmed and the complete state rules are met. | Record iPR and continue protocol-defined assessment; do not convert the category into an autonomous instruction to continue, de-escalate or stop therapy. Preserve the baseline sum, current sum, percent change, non-target state, new-lesion state and any earlier iUPD. | iPR does not supply an individual probability of survival, durable response or later progression. Apparent shrinkage after iUPD can reset the confirmation bar but does not retrospectively prove that the earlier finding was pseudoprogression. | Seymour et al. 2017, PMC5648544, Tables 1-3 and text on time-point response after iUPD; official RECIST Working Group iRECIST FAQ, post-iUPD iPR scenarios and reset logic, reviewed 2026-07-24. | ✓ |
| iSD | Immune stable disease | The evaluable timepoint meets neither iCR nor iPR and has no qualifying progression. After a prior iUPD, a later state may become iSD if progression is not confirmed and the component findings meet stable-disease rules; if findings are simply unchanged at the progression level without a reset state, retain iUPD. | Record iSD with the component measurements and continue the protocol-defined schedule. Stable disease is not synonymous with clinical stability, treatment benefit or absence of biologic progression, and it does not by itself choose therapy. | iSD is a heterogeneous response category with no universal prognosis. Duration, tumor biology, therapy and clinical course matter; never translate it into a fixed progression, survival or benefit estimate without cohort-specific evidence. | Seymour et al. 2017, PMC5648544, Table 1 and time-point response rules; Persigehl et al. 2020, PMC6942293, Responses to therapy; official iRECIST FAQ on unchanged findings versus post-iUPD response. | ✓ |
| iUPD | Immune unconfirmed progression | This is the first unconfirmed progression state: the fixed target sum has increased at least 20% from nadir and at least 5 mm absolutely, existing non-target disease has progressed unequivocally, or one or more new lesions have appeared. New lesions are tracked in separate target and non-target compartments and are not added to the baseline target sum. | If and only if the participant is clinically stable and the protocol/investigator permits treatment beyond progression, treatment may continue while imaging is repeated in 4-8 weeks. Clinical stability requires no performance-status worsening, no clinically relevant increase in disease-related symptoms and no need for intensified palliation. Clinical deterioration can require action without waiting for imaging confirmation. | iUPD is neither confirmed progression nor a diagnosis of pseudoprogression. The category supplies no probability that progression will confirm, no survival estimate and no assurance that waiting is safe; the protocol, symptoms and complete clinical state govern urgency. | Seymour et al. 2017, PMC5648544, Tables 1-3, New lesions and Continued treatment after iUPD sections; official RECIST Working Group iRECIST FAQ, 4-8-week timing and clinical-stability implementation reviewed 2026-07-24. | ✓ |
| iCPD | Immune confirmed progression | After a prior iUPD, the next evaluable assessment confirms additional progression through at least 5 mm further target-sum growth, any further non-target increase, at least 5 mm cumulative new-target-sum growth, any new-non-target increase, an additional new lesion, or qualifying progression in another disease compartment. The confirming event may differ from the compartment that triggered iUPD. | Record iCPD and backdate the immune progression event to the initial iUPD date when the prespecified analysis requires it. iCPD is a confirmed trial response state, not an automatic stop command: treatment decisions still follow the protocol, clinical assessment, participant preferences and investigator judgment. | iCPD supports confirmed radiologic progression within the iRECIST data framework but does not itself quantify survival, treatment resistance or immediate clinical danger. Prognosis and action require tumor-, therapy-, burden-, site- and patient-specific context. | Seymour et al. 2017, PMC5648544, Table 2 and confirmation/analysis sections; official RECIST Working Group iRECIST FAQ on target, non-target, new-lesion, cross-compartment, sequential-increment and event-date rules, reviewed 2026-07-24. | ✓ |

### Citações por categoria
- **iCR**: Seymour L, Bogaerts J, Perrone A, et al.. iRECIST: guidelines for response criteria for use in trials testing immunotherapeutics (2017) — https://pmc.ncbi.nlm.nih.gov/articles/PMC5648544/ · Seymour et al. 2017, PMC5648544, Table 1 (iCR and lymph-node rule), Table 2 and time-point response text; Persigehl et al. 2020, PMC6942293, section Responses to therapy.
- **iPR**: Seymour L, Bogaerts J, Perrone A, et al.. iRECIST: guidelines for response criteria for use in trials testing immunotherapeutics (2017) — https://pmc.ncbi.nlm.nih.gov/articles/PMC5648544/ · Seymour et al. 2017, PMC5648544, Tables 1-3 and text on time-point response after iUPD; official RECIST Working Group iRECIST FAQ, post-iUPD iPR scenarios and reset logic, reviewed 2026-07-24.
- **iSD**: Seymour L, Bogaerts J, Perrone A, et al.. iRECIST: guidelines for response criteria for use in trials testing immunotherapeutics (2017) — https://pmc.ncbi.nlm.nih.gov/articles/PMC5648544/ · Seymour et al. 2017, PMC5648544, Table 1 and time-point response rules; Persigehl et al. 2020, PMC6942293, Responses to therapy; official iRECIST FAQ on unchanged findings versus post-iUPD response.
- **iUPD**: Seymour L, Bogaerts J, Perrone A, et al.. iRECIST: guidelines for response criteria for use in trials testing immunotherapeutics (2017) — https://pmc.ncbi.nlm.nih.gov/articles/PMC5648544/ · Seymour et al. 2017, PMC5648544, Tables 1-3, New lesions and Continued treatment after iUPD sections; official RECIST Working Group iRECIST FAQ, 4-8-week timing and clinical-stability implementation reviewed 2026-07-24.
- **iCPD**: Seymour L, Bogaerts J, Perrone A, et al.. iRECIST: guidelines for response criteria for use in trials testing immunotherapeutics (2017) — https://pmc.ncbi.nlm.nih.gov/articles/PMC5648544/ · Seymour et al. 2017, PMC5648544, Table 2 and confirmation/analysis sections; official RECIST Working Group iRECIST FAQ on target, non-target, new-lesion, cross-compartment, sequential-increment and event-date rules, reviewed 2026-07-24.

## Referências cruzadas
- _fronteira compartilhada_ → [RECIST 1.1 — Response Evaluation Criteria in Solid Tumours v1.1](https://radcommons.laudos.ai/systems/recist-1-1.md) — iRECIST starts with RECIST 1.1 measurement rules but adds separate new-lesion tracking and a longitudinal iUPD/iCPD confirmation state machine for protocol-specified immunotherapy trials. Do not export the immune confirmation states into conventional RECIST 1.1.

## Histórico de versões

| Data | Evento | Detalhe | Situação |
| --- | --- | --- | --- |
| 2026-08-12 | revised | Monitored source changed (content_hash). Detected automatically; awaiting reviewer confirmation. | needs_review |
| 2026-08-07 | revised | Monitored source changed (content_hash). Detected automatically; awaiting reviewer confirmation. | needs_review |
| 2026-07-29 | revised | Monitored source changed (content_hash). Detected automatically; awaiting reviewer confirmation. | needs_review |
| 2026-07-25 | revised | Monitored source changed (content_hash). Detected automatically; awaiting reviewer confirmation. | needs_review |
| 2026-06-10 | revised | The official RECIST Working Group iRECIST implementation page and FAQ was updated with operational clarifications; it does not create a new numbered iRECIST version or convert the framework into a treatment guideline. | confirmed |
| 2017-03-01 | published | iRECIST guideline published. | confirmed |


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> Conteúdo de referência reescrito. Confira a publicação primária vigente. Não é dispositivo médico nem substitui o julgamento clínico. O radiologista responsável pelo laudo permanece o autor e o responsável.

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