A practical guide of the Southwest Oncology Group to measure malignant pleural mesothelioma tumors by RECIST and modified RECIST criteria

Our plain-English summary of A practical guide of the Southwest Oncology Group to measure malignant pleural mesothelioma tumors by RECIST and modified RECIST criteria, by A.S. Tsao, L. Garland, M. Redman, et al (Journal of Thoracic Oncology, 2011).

The study

• Authors: A.S. Tsao, L. Garland, M. Redman, K. Kernstine, D. Gandara, E.M. Marom
• Journal: Journal of Thoracic Oncology
• Published: 2011;6(3):598-601
• Cited by: 29 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Malignant pleural mesothelioma (MPM) is difficult to measure radiographically due to the nonradial and variable pattern of growth and response to therapy. Inaccurate and inconsistent tumor measurements often compromise results from clinical trials that are dependent on identifying response rate and progression-free survival. In this article, we sought to provide a practical guide through the Southwest Oncology Group on how to measure MPM by the updated RECIST version 1.1 and by modified RECIST. We hope that these steps will provide a simple means by which computed tomography measurements can be consistently performed, minimizing intra- and interobserver variability. With this consistency, we may be able to better estimate the prognosis and response to therapy. With greater utilization, we will be able to better understand the biology of MPM.

In plain English

This article was a practical guide from the Southwest Oncology Group, not a study of patients. It explained how to measure malignant pleural mesothelioma on CT scans for clinical trials, and it did not discuss asbestos exposure. The authors explained two existing methods. Under RECIST version 1.1, the longest diameter of the tumor along the chest wall is measured, and only two pleural measurements are used. Under modified RECIST, tumor thickness is measured perpendicular to the chest wall or mediastinum at two sites on each of three CT slices, and the six measurements are added together. The authors' tips included using the "soft tissue" window setting, preferring thin 2.5 mm slices, having the same clinician measure every scan, treating pleural disease under 1 cm as nonmeasurable, and avoiding spots where tumor meets muscle. In a worked example of one patient, the total was 22.4 cm by RECIST version 1.1 and 22.1 cm by modified RECIST, each including a 3.3 cm lymph node. The authors wrote that educating clinicians and standardizing measurement is essential.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Practical methods guide (instructions for measuring tumors on CT scans), with a worked example from one patient; not a study of a patient group
• Who was studied: No patient population was studied; the figures illustrate measurements in an example patient with malignant pleural mesothelioma
• Main results:
  • Under RECIST version 1.1, the longest diameter of a rind-like pleural tumor is measured along the chest wall, and only two pleural tumor measurements are required
  • Under modified RECIST, two measurements are taken on each of three different CT slices, preferably above the level of the main bronchi, giving six measurements
  • The authors recommended the soft tissue window setting rather than lung windows
  • CT slices up to 5 mm can be used, but thinner 2.5 mm slices are preferred
  • The same clinician should preferably measure the tumors at baseline and on all later scans
  • Pleural disease less than 1 cm is considered nonmeasurable
  • Measurers should avoid places where tumor meets muscle, because the two look similar on CT
  • Worked example, RECIST version 1.1: pleura 10.9 plus 8.2 equals 19.1 cm, plus a 3.3 cm lymph node, gives a total of 22.4 cm
  • Worked example, modified RECIST: six pleural measurements summing to 18.8 cm, plus the 3.3 cm lymph node, gives a total of 22.1 cm
• The authors' conclusion: The authors concluded that educating clinicians in applying RECIST and modified RECIST, and standardizing how measurements are made, is essential

Topics

The National Library of Medicine indexes this study under subjects our site covers: Mesothelioma.

Medical terms in this study, explained in our Lexicon: Pleural Mesothelioma, Modified RECIST (mRECIST), Clinical Trial, Progression-Free Survival, Prognosis.

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