What is RECIST 1.1?

This post is part of 'Domain | General' series

RECIST (Response Evaluation Criteria In Solid Tumors) is a set of guidelines developed by an international panel of experts to standardize the evaluation of solid tumors in clinical trials. RECIST 1.1 is the latest version of these guidelines, released in 2009, and it builds on the previous version, RECIST 1.0.

RECIST 1.1 provides a standardized method for assessing tumor response in solid tumors treated with chemotherapy, targeted therapy, or immunotherapy. The primary endpoint in most oncology clinical trials is tumor response, which is a measure of how much the tumor shrinks or grows after treatment. RECIST 1.1 defines four categories of tumor response: complete response (CR), partial response (PR), stable disease (SD), and progressive disease (PD).

Complete Response (CR) A CR is defined as the disappearance of all target lesions and the absence of any new lesions. Additionally, there must be no evidence of disease-related symptoms. A CR is considered the best possible outcome in terms of tumor response.

Partial Response (PR) A PR is defined as at least a 30% decrease in the sum of the longest diameters (LDs) of target lesions compared to baseline. Additionally, there must be no evidence of new lesions or disease progression in non-target lesions. The patient must also demonstrate an improvement in disease-related symptoms.

Stable Disease (SD) SD is defined as neither sufficient shrinkage to qualify for PR nor sufficient increase to qualify for PD. In other words, the sum of the LDs of target lesions must not have decreased by at least 30% or increased by at least 20% compared to baseline. Additionally, there must be no evidence of new lesions. The patient must also not demonstrate any worsening of disease-related symptoms.

Progressive Disease (PD) PD is defined as at least a 20% increase in the sum of the LDs of target lesions compared to the smallest sum recorded since the start of treatment. Additionally, there must be an absolute increase of at least 5mm in the sum of the LDs of target lesions. Alternatively, the appearance of one or more new lesions is also considered PD. The patient must also demonstrate an increase in disease-related symptoms.

RECIST 1.1 provides detailed instructions for measuring lesions, selecting target lesions, and assessing non-target lesions. In addition, it provides guidance on what to do when there is a discrepancy in lesion measurement between different radiologists, how to handle missing data, and how to evaluate the overall response in cases where there are multiple lesions.

In conclusion, RECIST 1.1 is an essential tool for assessing tumor response in clinical trials of solid tumors. Its standardized approach enables clinicians and researchers to accurately and consistently evaluate the efficacy of different treatments and compare the results of different trials. Understanding RECIST 1.1 guidelines and ensuring compliance with them is critical for obtaining valid and reliable results from clinical trials in oncology.


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