**Response Evaluation Criteria in Solid Tumors (RECIST) Quick
Reference:**

# Eligibility

# Only patients with measurable disease at baseline should be included in protocols where objective tumor response is the primary endpoint. 

# Measurable disease - the presence of at least one measurable lesion. If the measurable disease is restricted to a solitary lesion, its neoplastic nature should be confirmed by cytology/histology. 

**Measurable lesions** - lesions that can be accurately measured in at
least one dimension with longest diameter ≥20 mm using conventional
techniques or ≥10 mm with spiral CT scan.

**Non-measurable** **lesions** - all other lesions, including small
lesions (longest diameter \<20 mm with conventional techniques or \<10
mm with spiral CT scan), i.e., bone lesions, leptomeningeal disease,
ascites, pleural/pericardial effusion, inflammatory breast disease,
lymphangitis cutis/pulmonis, cystic lesions, and also abdominal masses
that are not confirmed and followed by imaging techniques; and.

-   All measurements should be taken and recorded in metric notation,
    using a ruler or calipers. All baseline evaluations should be
    performed as closely as possible to the beginning of treatment and
    never more than 4 weeks before the beginning of the treatment.

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-   The same method of assessment and the same technique should be used
    to characterize each identified and reported lesion at baseline and
    during follow-up.

-   Clinical lesions will only be considered measurable when they are
    superficial (e.g., skin nodules and palpable lymph nodes). For the
    case of skin lesions, documentation by color photography, including
    a ruler to estimate the size of the lesion, is recommended.

### Methods of Measurement -- 

-   CT and MRI are the best currently available and reproducible methods
    to measure target lesions selected for response assessment.
    Conventional CT and MRI should be performed with cuts of 10 mm or
    less in slice thickness contiguously. Spiral CT should be performed
    using a 5 mm contiguous reconstruction algorithm. This applies to
    tumors of the chest, abdomen and pelvis. Head and neck tumors and
    those of extremities usually require specific protocols.

-   Lesions on chest X-ray are acceptable as measurable lesions when
    they are clearly defined and surrounded by aerated lung. However, CT
    is preferable.

-   When the primary endpoint of the study is objective response
    evaluation, ultrasound (US) should not be used to measure tumor
    lesions. It is, however, a possible alternative to clinical
    measurements of superficial palpable lymph nodes, subcutaneous
    lesions and thyroid nodules. US might also be useful to confirm the
    complete disappearance of superficial lesions usually assessed by
    clinical examination.

-   The utilization of endoscopy and laparoscopy for objective tumor
    evaluation has not yet been fully and widely validated. Their uses
    in this specific context require sophisticated equipment and a high
    level of expertise that may only be available in some centers.
    Therefore, the utilization of such techniques for objective tumor
    response should be restricted to validation purposes in specialized
    centers. However, such techniques can be useful in confirming
    complete pathological response when biopsies are obtained.

-   Tumor markers alone cannot be used to assess response. If markers
    are initially above the upper normal limit, they must normalize for
    a patient to be considered in complete clinical response when all
    lesions have disappeared.

-   Cytology and histology can be used to differentiate between PR and
    CR in rare cases (e.g., after treatment to differentiate between
    residual benign lesions and residual malignant lesions in tumor
    types such as germ cell tumors).

**Baseline documentation of "Target" and "Non-Target" lesions**

-   All measurable lesions up to a maximum of five lesions per organ and
    10 lesions in total, representative of all involved organs should be
    identified as ***target lesions*** and recorded and measured at
    baseline.

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-   Target lesions should be selected on the basis of their size
    (lesions with the longest diameter) and their suitability for
    accurate repeated measurements (either by imaging techniques or
    clinically).

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-   A sum of the longest diameter (LD) for *all target lesions* will be
    calculated and reported as the baseline sum LD. The baseline sum LD
    will be used as reference by which to characterize the objective
    tumor.

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-   All other lesions (or sites of disease) should be identified as
    ***non-target lesions*** and should also be recorded at baseline.
    Measurements of these lesions are not required, but the presence or
    absence of each should be noted throughout follow-up.

## Response Criteria

### Evaluation of target lesions

  ------------------ ----------------------------------------------------
  \* Complete        Disappearance of all target lesions
  Response (CR):     

  \* Partial         At least a 30% decrease in the sum of the LD of
  Response (PR):     target lesions, taking as reference the baseline sum
                     LD

  \* Progressive     At least a 20% increase in the sum of the LD of
  Disease (PD):      target lesions, taking as reference the smallest sum
                     LD recorded since the treatment started or the
                     appearance of one or more new lesions

  \* Stable Disease  Neither sufficient shrinkage to qualify for PR nor
  (SD):              sufficient increase to qualify for PD, taking as
                     reference the smallest sum LD since the treatment
                     started
  ------------------ ----------------------------------------------------

### Evaluation of non-target lesions

  ------------------ ----------------------------------------------------
  \* Complete        Disappearance of all non-target lesions and
  Response (CR):     normalization of tumor marker level

  \* Incomplete      Persistence of one or more non-target lesion(s)
  Response/ Stable   or/and maintenance of tumor marker level above the
  Disease (SD):      normal limits

  \* Progressive     Appearance of one or more new lesions and/or
  Disease (PD):      unequivocal progression of existing non-target
                     lesions (1)
  ------------------ ----------------------------------------------------

### Although a clear progression of "non target" lesions only is exceptional, in such circumstances, the opinion of the treating physician should prevail and the progression status should be confirmed later on by the review panel (or study chair). 

### Evaluation of best overall response

The best overall response is the best response recorded from the start
of the treatment until disease progression/recurrence (taking as
reference for PD the smallest measurements recorded since the treatment
started). In general, the patient\'s best response assignment will
depend on the achievement of both measurement and confirmation criteria

  ----------------- -------------------- ---------------- -----------------
  Target lesions    Non-Target lesions   New Lesions      Overall response

  CR                CR                   No               CR

  CR                Incomplete           No               PR
                    response/SD                           

  PR                Non-PD               No               PR

  SD                Non-PD               No               SD

  PD                Any                  Yes or No        PD

  Any               PD                   Yes or No        PD

  Any               Any                  Yes              PD
  ----------------- -------------------- ---------------- -----------------

### 

### Patients with a global deterioration of health status requiring discontinuation of treatment without objective evidence of disease progression at that time should be classified as having "symptomatic deterioration". Every effort should be made to document the objective progression even after discontinuation of treatment. 

### In some circumstances it may be difficult to distinguish residual disease from normal tissue. When the evaluation of complete response depends on this determination, it is recommended that the residual lesion be investigated (fine needle aspirate/biopsy) to confirm the complete response status.

### Confirmation

-   The main goal of confirmation of objective response is to avoid
    overestimating the response rate observed. In cases where
    confirmation of response is not feasible, it should be made clear
    when reporting the outcome of such studies that the responses are
    not confirmed.

-   To be assigned a status of PR or CR, changes in tumor measurements
    must be confirmed by repeat assessments that should be performed no
    less than 4 weeks after the criteria for response are first met.
    Longer intervals as determined by the study protocol may also be
    appropriate.

-   In the case of SD, follow-up measurements must have met the SD
    criteria at least once after study entry at a minimum interval (in
    general, not less than 6-8 weeks) that is defined in the study
    protocol

### Duration of overall response

-   The duration of overall response is measured from the time
    measurement criteria are met for CR or PR (whichever status is
    recorded first) until the first date that recurrence or PD is
    objectively documented, taking as reference for PD the smallest
    measurements recorded since the treatment started.

### Duration of stable disease

-   SD is measured from the start of the treatment until the criteria
    for disease progression are met, taking as reference the smallest
    measurements recorded since the treatment started.

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-   The clinical relevance of the duration of SD varies for different
    tumor types and grades. Therefore, it is highly recommended that the
    protocol specify the minimal time interval required between two
    measurements for determination of SD. This time interval should take
    into account the expected clinical benefit that such a status may
    bring to the population under study.

# Response review

-   For trials where the response rate is the primary endpoint it is
    strongly recommended that all responses be reviewed by an expert(s)
    independent of the study at the study's completion. Simultaneous
    review of the patients' files and radiological images is the best
    approach.

# Reporting of results

# All patients included in the study must be assessed for response to treatment, even if there are major protocol treatment deviations or if they are ineligible. Each patient will be assigned one of the following categories: 1) complete response, 2) partial response, 3) stable disease, 4) progressive disease, 5) early death from malignant disease, 6) early death from toxicity, 7) early death because of other cause, or 9) unknown (not assessable, insufficient data).

# All of the patients who met the eligibility criteria should be included in the main analysis of the response rate. Patients in response categories 4-9 should be considered as failing to respond to treatment (disease progression). Thus, an incorrect treatment schedule or drug administration does not result in exclusion from the analysis of the response rate. Precise definitions for categories 4-9 will be protocol specific.

# All conclusions should be based on all eligible patients.

# Subanalyses may then be performed on the basis of a subset of patients, excluding those for whom major protocol deviations have been identified (e.g., early death due to other reasons, early discontinuation of treatment, major protocol violations, etc.). However, these subanalyses may not serve as the basis for drawing conclusions concerning treatment efficacy, and the reasons for excluding patients from the analysis should be clearly reported. 

# The 95% confidence intervals should be provided.

##