Correlation of patient survival with clinical tumor measurements in malignant pleural mesothelioma

Our plain-English summary of Correlation of patient survival with clinical tumor measurements in malignant pleural mesothelioma, by F. Li, M. Ahmad, F. Qayyum, et al (European Radiology, 2019).

The study

• Authors: F. Li, M. Ahmad, F. Qayyum, C.M. Straus, H. MacMahon, H. Kindler, S.G. Armato
• Journal: European Radiology
• Published: 2019;29(6):2981-2988
• Type of article: Randomized trial
• Cited by: 4 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Objectives: To evaluate differences in the tumor response classifications that result from clinical measurements and to compare these response classifications with overall survival for patients with malignant pleural mesothelioma (MPM).

Methods: One hundred thirty-one computed tomography (CT) scans were collected from 41 MPM patients enrolled in a clinical trial. Primary measurements had been acquired by clinical radiologists at a single center during routine clinical workflow, and the variability of these measurements was investigated. Retrospective measurements were acquired by a single radiologist in compliance with the study protocol based on the modified response evaluation criteria in solid tumors (RECIST). Differences in response classification categories by the two measurement approaches were evaluated and compared with patient survival.

Results: Eleven (27%) of the 41 MPM patients had primary measurements at baseline or at follow-up that deviated from the guidelines of the clinical trial protocol. Among the 41 baseline scans, no statistical difference was observed in summed tumor measurements between primary and retrospective measurements. Response classification based on primary and retrospective measurements was different in 23 (26%) of the 90 follow-up scans, and best response was the different in seven (17%) of the 41 patients. Using Harrell's C statistic as a measure of correlation, response based on retrospective measurements correlated better with survival (C = 0.62) than did response based on primary measurements (C = 0.57).

Conclusions: Strict compliance with the measurement protocol yields tumor response classifications that may differ from those obtained in clinical practice. Response based on retrospective measurements correlated better with survival than did response based on primary measurements.

Key Points: • Response classifications could be different between clinical primary and retrospective measurements for malignant pleural mesothelioma. • Response classifications obtained by strict compliance with the trial-specific protocol correlated better with survival than the classifications based on primary measurements. • Quality assurance and radiologist training measures should be used to ensure the integrity of image-based tumor measurements in mesothelioma clinical trials.

In plain English

This retrospective study looked at CT scans of 41 patients with advanced malignant pleural mesothelioma. All had prior chemotherapy and were enrolled, at one medical center, in a trial of vorinostat versus placebo. The study did not examine asbestos exposure. The authors compared tumor measurements made during routine clinical work (by 13 radiologists, on 131 scans) with measurements made later by one study radiologist following the trial's rules (modified RECIST). Routine measurements for 11 of the 41 patients departed from those rules. On the first scans, summed tumor sizes did not differ significantly between approaches. Response category differed in 23 of 90 follow-up scans, and best response in 7 of 41 patients. Best response from the rule-following measurements matched survival somewhat better (C statistic 0.62, 95% confidence interval 0.57 to 0.67) than from routine measurements (0.57, 95% confidence interval 0.52 to 0.62), but this difference was not statistically significant. The authors concluded that strict protocol compliance can give response classifications that differ from clinical practice. They noted the single trial, single center and single study radiologist as limitations.

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: Retrospective study at one institution comparing two sets of CT tumor measurements (routine clinical versus protocol-compliant) and relating each to patient survival
• Who was studied: 41 patients with advanced malignant pleural mesothelioma (33 men, 8 women; ages 48 to 84, mean 67.6), previously treated with chemotherapy, enrolled at a single center in a phase III trial run from 2006 to 2012. The study used 131 CT scans: 41 baseline and 90 follow-up.
• Exposure: Asbestos exposure was not studied. The study concerned CT measurement methods in patients from a trial of vorinostat versus placebo.
• Main results:
  • Routine clinical measurements for 11 of the 41 patients deviated from modified RECIST.
  • On the 41 baseline scans there was no statistically significant difference between summed routine and summed protocol-compliant measurements (p = 0.78).
  • Response classification differed between the two approaches in 23 (26%) of 90 follow-up scans.
  • Best response differed between the two approaches in 7 (17%) of 41 patients.
  • Correlation of best response with overall survival was C = 0.62 (95% CI 0.57 to 0.67) for protocol-compliant measurements and C = 0.57 (95% CI 0.52 to 0.62) for routine measurements.
  • The difference between C = 0.62 (protocol-compliant) and C = 0.57 (routine) was not statistically significant.
  • When only measurement sites of at least 10 mm at baseline were used, C fell from 0.62 to 0.52 for protocol-compliant measurements.
  • When only measurement sites of at least 10 mm at baseline were used, C fell from 0.57 to 0.38 (95% CI 0.32 to 0.44) for routine measurements.
• The authors' conclusion: The authors concluded that strict compliance with the measurement protocol yields tumor response classifications that may differ from those obtained in clinical practice.
• Limitations the authors state:
  • Patients came from a single clinical trial at one medical center.
  • All protocol-compliant measurements were made by a single study radiologist.
  • The study used the actual radiology reports, not the case report forms that send measurements to the trial sponsor.
  • The small number of cases likely limited the ability to detect statistically significant differences in the C statistic.
  • Vorinostat was ineffective in this cohort, so very few patients responded.

Topics

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

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

Related studies

• Variability of tumor area measurements for response assessment in malignant pleural mesothelioma — Z.E. Labby, C. Straus, et al. (2013)
• Observer variability in mesothelioma tumor thickness measurements: defining minimally measurable lesions — S.G. Armato, A.K. Nowak, et al. (2014)
• Diffuse mesothelioma of the peritoneum: correlation between histological and clinical parameters and survival in 73 patients — S. Liu, P. Staats, et al. (2014)
• Assessment of therapy responses and prediction of survival in malignant pleural mesothelioma through computer-aided volumetric measurement on computed tomography scans — F. Liu, B. Zhao, et al. (2010)
• Epithelial malignant pleural mesothelioma after extrapleural pneumonectomy: stratification of survival with CT-derived tumor volume — R.R. Gill, W.G. Richards, et al. (2012)
• High-resolution CT of benign asbestos-related diseases: clinical and radiographic correlation — D.R. Aberle, G. Gamsu, et al. (1988)

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