Updated Modified RECIST to Better Evaluate Treatment Response in Mesothelioma

The Response Evaluation Criteria in Solid Tumors (RECIST) was established nearly two decades ago by the European Organization for Research and Treatment of Cancer and the National Cancer Institute of the United States. The purpose of these published rules was to universally define when cancerous tumors stabilize, progress, or just respond to any given treatment. Having set criteria allows doctors and researchers describe tumor changes; this helps ensure that evaluations regarding the response to a drugs is as objective as possible. However, in 2004, RECIST was modified because it was considered too restrictive as some tumor shapes, like those associated with mesothelioma, are irregular and difficult to measure by following a standard procedure. Since then, modified RECIST has been customary.

To apply the RECIST guidelines for mesothelioma, patients must have at least one tumor that is able to be measured with imaging techniques (CT scans, MRIs and, X-rays) for a basis of comparison. These tumors (typically referred to as “lesions”) are measured after treatment has been administered to assess:

• Complete Response – targeted tumors have responded and disappeared throughout course of treatment
• Partial Response – At least 30 percent of tumors have decreased in size
• Stable Disease – No change in tumor progression, but no decrease in tumor size either
• Progressive Disease – Tumor has increased in size by at least 20 percent

The growth pattern of pleural mesothelioma tumors is unusual, therefore making the use of RECIST somewhat difficult. As previously mentioned, RECIST was modified in order to allow scientists and researchers to better evaluate, but a recent assessment of RECIST published in the Journal of Thoracic Oncology revised the modified RECIST criteria and recommends that this new version, “modified RECIST 1.1” be used in evaluations moving forward.

This updated criterion is to take a closer look at defining tumor characteristics and measurements, location, and establishing progressive disease.  Author SG Armato states that these modified RECIST 1.1 guidelines:

“Collate and apply research published since the development of modified RECIST, align modified RECIST with RECIST 1.1, address those aspects of tumor measurement that were neglected or not well characterized in the modified RECIST paper, and clarify ambiguous or difficult measurement issues that have been highlighted through the subsequent decade of clinical trials research.”

Mesothelioma has been notoriously difficult to treat. There is no cure for mesothelioma and many who are suffering participate in clinical trials in hopes of finding a successful treatment. Evaluating drug response through RECIST ensures that doctors are giving their patients the best treatment possible that is uniquely targeted for the patient.

Source:

Armato, SG 3^rd, et. al., “Revised Modified RECIST Criteria for Assessment of Response in Malignant Pleural Mesothelioma (Version 1.1)”, Journal of Thoracic Oncology (May 9, 2018). [Link]