“A Guide on Tumor Response and Progression (RECIST) While on Cancer Therapy”
Concept of RECIST
RECIST is a standardized set of guidelines used primarily in clinical cancer research. It was developed to provide a uniform way to measure how solid tumors (those forming lumps) respond to treatment, especially in clinical trials. This standardization is crucial for comparing the efficacy of different treatments and determining whether patients benefit from a specific therapy.
Key Elements of RECIST
1. Target Lesions Selection: In RECIST, doctors select a subset of all present tumors, known as "target lesions," to monitor. These lesions are measured at the beginning of the study and serve as a baseline for comparison. They are usually up to five per organ and ten in total.
2. Non-Target Lesions: Other lesions are not measured precisely but are still monitored for the presence or absence of disease.
3. Measuring Changes in Tumor Size: The size of these target lesions is measured using imaging techniques like CT scans or MRIs. The sum of the longest diameter of these target lesions is calculated.
4. Categorizing Treatment Response:
Complete Response (CR): Disappearance of all target lesions.
Partial Response (PR): At least a 30% decrease in the sum of diameters of target lesions, taking as reference the baseline sum diameters.
Progressive Disease (PD): At least a 20% increase in the sum of diameters of target lesions, taking as reference the smallest sum on study. In addition, the sum must also show an absolute increase of at least 5 mm.
Stable Disease (SD): Neither sufficient shrinkage to qualify for PR nor sufficient increase to qualify for PD.
Importance of RECIST
Standardization: RECIST provides a standardized way to report the effects of cancer treatment, which is particularly important in comparing results across different clinical trials.
Objectivity: By using specific criteria, RECIST aims to eliminate subjective interpretation of tumor response, making it more objective.
Decision Making: It helps in clinical decision-making, allowing oncologists to determine whether to continue, change, or stop treatment based on tumor response.
Limitations and Evolutions
RECIST 1.1: The original RECIST guidelines were updated to RECIST 1.1 to address some limitations, such as clarifying definitions and reducing the number of lesions to be measured.
Limitations: RECIST primarily focuses on tumor size, not necessarily capturing other aspects of tumor behavior or patient health. It may not be as effective for evaluating certain treatments, like immunotherapies, which can cause tumors to swell (pseudo-progression) before shrinking.
In Summary
RECIST is a pivotal tool in oncology research and treatment, providing a common language for evaluating the effectiveness of cancer therapies. Its use helps to determine the best course of action for patient care and guides the development of new cancer treatments. However, it's important to understand its limitations and the context in which it is most effectively used.
To learn more about RECIST and its application, exploring resources like academic journal articles or detailed explanations from cancer research institutions can provide a more comprehensive understanding.
