Response Evaluation Criteria in Solid Tumors (RECIST)

Most common evaluation tool used to assess tumor response in solid tumors.

Categorizes quantitative tumor size changes into complete response, partial response, stable disease, or progressive disease.

Criteria were generated from cytotoxic chemotherapy trial data.

Complete response-disappearance of all target lesions, partial response-equal to or greater than 30% decrease in the sum of the longest dimension of target lesions, relative to baseline measurement, stable disease-decrease in tumor size of <30% or increase of <20%, progressive disease-equal or greater than 20% increase in the sum of the longest dimension of target lesions.

One dimensional tumor measurements that have become the standard criteria to determine tumor response.

Has limited assessment value of molecularly targeted agents as the cut off of 30% change in the sum of the longest diameter is as the criteria response may not adequately capture potentially effective therapies.

Response Evaluation Criteria In Solid Tumors (RECIST) is a set of rules that define when tumors in cancer patients improve respond, stay the same or worsen during treatment.

Published in February 2000 by an international collaboration including the European Organisation for Research and Treatment of Cancer(EORTC), National Cancer Institute of the United States, and the National Cancer Institute of Canada Clinical Trials Group.

Majority of clinical trials evaluating cancer treatments for objective response in solid tumors use RECIST.

These criteria were updated in 2009.

Measurable disease – the presence of at least one measurable lesion.

Measurable lesions – lesions that can be accurately measured in at least one dimension with longest diameter ≥20 mm using conventional techniques or ≥10 mm by 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.

Baseline evaluations should be performed at the beginning of treatment and never more than 4 weeks before the beginning of treatment.

Clinical lesions will only be considered measurable when they are superficial (e.g., skin nodules and palpable lymph nodes).

CT and MRI are the best currently available and reproducible methods to measure target lesions selected for response assessment.

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.

The utilization of endoscopy and laparoscopy for objective tumor evaluation has not yet been fully and widely validated.

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.

Rarely, pathology can be used to differentiate between partial and complete remission.

All measurable lesions up to a maximum of 2 lesions per organ and 5 lesions in total, representative of all involved organs should be identified as target lesions and recorded and measured at baseline.

Target lesions should be selected on the basis of their size and their suitability for accurate repeated measurements.

Response criteria.

Complete Response (CR): Disappearance of all target lesions

Partial Response (PR): At least a 30% decrease in the sum of the longest diameter of target lesions, taking as reference the baseline sum longest diameter.

Stable Disease (SD): Neither sufficient shrinkage to qualify for PR nor sufficient increase to qualify for PD, taking as reference the smallest sum longest diameter since the treatment started.

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

Evaluation of non-target lesions:

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

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

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

Patients with a deterioration of health status requiring discontinuation of treatment without objective evidence of disease progression at that time are classified as having “symptomatic deterioration”.

Residual lesions should be investigated by fine needle aspirate/biopsy to confirm the complete response status.

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

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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