Imaging response assessment for oncology: An algorithmic approach

Our plain-English summary of Imaging response assessment for oncology: An algorithmic approach, by K. Ruchalski, R. Dewan, V. Sai, et al (European Journal of Radiology Open, 2022).

The study

• Authors: K. Ruchalski, R. Dewan, V. Sai, L.J. McIntosh, M. Braschi-Amirfarzan
• Journal: European Journal of Radiology Open
• Published: 2022;9:100426
• Cited by: 9 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Treatment response assessment by imaging plays a vital role in evaluating changes in solid tumors during oncology therapeutic clinical trials. Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 is the reference standard imaging response criteria and provides details regarding image acquisition, image interpretation and categorical response classification. While RECIST 1.1 is applied for the majority of clinical trials in solid tumors, other criteria and modifications have been introduced when RECIST 1.1 outcomes may be incomplete. Available criteria beyond RECIST 1.1 can be explored in an algorithmic fashion dependent on imaging modality, tumor type and method of treatment. Positron Emission Tomography Response Criteria in Solid Tumors (PERCIST) is available for use with PET/CT. Modifications to RECIST 1.1 can be tumor specific, including mRECIST for hepatocellular carcinoma and mesothelioma. Choi criteria for gastrointestinal stromal tumors incorporate tumor density with alterations to categorical response thresholds. Prostate Cancer Working Group 3 (PCWG3) imaging criteria combine RECIST 1.1 findings with those of bone scans. In addition, multiple response criteria have been created to address atypical imaging responses in immunotherapy.

© 2022 The Authors. Published by Elsevier Ltd.

In plain English

This review, not a patient study, described imaging rules cancer drug trials use to judge whether tumors shrink or grow; it proposed choosing among them by imaging method, tumor type and treatment. It does not discuss asbestos. Under standard RECIST 1.1 rules, progression is a rise of 20% or more (at least 5 mm) in summed diameters of selected tumors over the first or smallest measurement, or any new malignant lesion or clear worsening of other disease; partial response is a fall of at least 30% from baseline. Malignant pleural mesothelioma, the authors noted, grows along the chest lining, which RECIST 1.1 captures poorly because it assumes round tumors. The mesothelioma version (mRECIST) measures pleural thickening of at least 10 mm at up to two places on three scan levels. There, a 30% or greater decrease is partial response; a 20% or greater increase over the smallest measurement, or a new lesion, is progression. The review also covered immunotherapy, PET scans, gastrointestinal stromal tumors, liver and prostate cancer, for which the authors concluded criteria beyond RECIST 1.1 are available.

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: Narrative review of imaging response criteria used in oncology clinical trials, organized as an algorithm.
• Who was studied: No study population. The article reviews published response criteria: RECIST 1.1, irRC, irRECIST, imRECIST, iRECIST, PERCIST, Choi criteria, mRECIST for hepatocellular carcinoma and for mesothelioma, and PCWG3. It is illustrated with images from individual patients, including an 82-year-old man with malignant pleural mesothelioma.
• Exposure: Not applicable; the article does not discuss asbestos or any other exposure.
• Main results:
  • Under RECIST 1.1, disease progression is a relative increase of 20% or more (at least 5 mm absolute) in the sum of diameters compared with baseline or nadir. Any new malignant lesion also meets criteria for progression.
  • Under RECIST 1.1, unequivocal worsening of non-target disease also defines progression. The article states this in its comparison with iRECIST and in Table 1.
  • Under RECIST 1.1, partial response is a decrease of at least 30% in the sum of diameters from baseline.
  • The authors stated that the circumferential growth of mesothelioma along the pleura is not well characterized by RECIST 1.1 because of its spherical assumptions.
  • Under mRECIST for mesothelioma, pleural thickening of at least 10 mm in short axis can be measured in up to two locations at three separate axial levels.
  • Under mRECIST for mesothelioma, partial response is a decrease in total tumor measurement of at least 30%.
  • Under mRECIST for mesothelioma, disease progression is an increase of 20% or more in total tumor measurement over the nadir, or new lesions (per Table 1).
  • Immunotherapy-specific criteria share a common feature: they allow treatment to continue beyond RECIST 1.1 progression in patients who are not clinically deteriorating.
  • Under the Choi criteria for gastrointestinal stromal tumors, partial response is a decrease in size of at least 10% or a decrease in tumor density of at least 15% on CT.
  • Under PCWG3, progression based on bone disease alone requires 2 or more new lesions on bone scan, confirmed 6 or more weeks later by at least 2 additional new lesions.
• The authors' conclusion: The authors concluded that RECIST 1.1 remains the reference standard. They stated that multiple additional criteria are available for certain tumor types, for immunotherapy, and for PET imaging, and that understanding these criteria is essential for patient care and trial reporting.

Topics

Medical terms in this study, explained in our Lexicon: Clinical Trial, Carcinoma, Mesothelioma, Immunotherapy.

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