Volumetry: an alternative to assess therapy response for malignant pleural mesothelioma?

Our plain-English summary of Volumetry: an alternative to assess therapy response for malignant pleural mesothelioma?, by T. Frauenfelder, M. Tutic, W. Weder, et al (The European Respiratory Journal, 2011).

The study

• Authors: T. Frauenfelder, M. Tutic, W. Weder, R.P. Götti, R.A. Stahel, B. Seifert, I. Opitz
• Journal: The European Respiratory Journal
• Published: 2011;38(1):162-8
• Cited by: 80 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

The purpose of our study was to assess robustness of volumetric measurement of malignant pleural mesothelioma (MPM) before and after chemotherapy to modified RECIST (response evaluation criteria in solid tumours) criteria. 30 patients with digitally available chest computed tomography (CT) scans before and after three cycles of chemotherapy were included. Three readers independently assessed tumour response using two different methods: 1) the modified RECIST criteria; and 2) the tumour volumetric approach using dedicated software (Myrian; Intrasense, Paris, France). Inter-rater reliability of unidimensional and volumetric measurements was assessed using intraclass correlation. Tumour response classification for modified RECIST was compared to the volumetric approach applying unidimensional RECIST volumetric equivalent criteria. The determination of unidimensional tumour measurement (RECIST) revealed a low inter-rater reliability (0.55) and a low interobserver agreement for tumour response classification (general κ 0.33). Only 14 patients were classified equally. A high inter-rater reliability (0.99) and interobserver agreement (general κ 0.9) were found for absolute tumour volumes (volumetric measurements). 27 cases were classified equally. The number of cases classified as "stable disease" was higher for the volumetric approach using tumour-equivalent criteria compared to modified RECIST. Volumetric measurement of MPM on CT using Myrian software is a reliable, reproducible and sensitive method to measure tumour volume and, thus, therapy response after induction chemotherapy.

In plain English

This study compared two ways of measuring malignant pleural mesothelioma on chest CT scans before and after three cycles of chemotherapy. The authors looked back at scans from 30 patients (28 men, 2 women) treated in Zurich with induction chemotherapy followed by extrapleural pneumonectomy. Three readers measured each tumour independently by modified RECIST, in which each reader chooses where to measure tumour thickness (two positions on each of three levels), and by software (Myrian) that calculates total tumour volume. With modified RECIST, the readers agreed on the response category in 14 of 30 cases. Agreement scores were 0.33 (general kappa) and 0.55 (intraclass correlation). With volumetry, the scores were 0.89 and 0.99. Changes measured by the two methods were moderately correlated (0.45 to 0.67, depending on the reader). Many cases rated partial response or stable disease by modified RECIST would have been rated stable or progressive disease by volumetry. The authors concluded that volumetry is reproducible and reliable, with higher agreement between readers than modified RECIST. They noted the small number of patients and that volumetry took 10 to 15 minutes per reading. The article did not address asbestos exposure.

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 imaging study comparing two CT measurement methods (modified RECIST and software-based tumour volumetry), each applied independently by three readers
• Who was studied: 30 patients with biopsy-proven malignant pleural mesothelioma (stage cT1–3 cN0–2 cM0) at the University Hospital Zurich, Switzerland, scanned between May 1999 and January 2008; median age 60 years (range 48 to 71); 2 women and 28 men; all treated with induction chemotherapy followed by extrapleural pneumonectomy
• Exposure: The article did not study or report asbestos exposure. The patients received three cycles of induction chemotherapy: cisplatin with gemcitabine (2 patients) or cisplatin with pemetrexed (28 patients).
• Main results:
  • Modified RECIST: the three readers classified tumour response identically in 14 of 30 cases
  • Modified RECIST: the general kappa between the three readers was 0.33
  • Modified RECIST: the intraclass correlation coefficient for tumour response was 0.55, which the authors described as poor
  • Volumetry: the general kappa between the three readers was 0.89
  • Volumetry: the intraclass correlation coefficient for tumour response was 0.99 across all three readers
  • The changes measured by modified RECIST and by volumetry were correlated at 0.57 (reader 1), 0.67 (reader 2) and 0.45 (reader 3), which the authors called a moderate correlation
  • The two methods gave conflicting response classifications in 8 cases (reader 1), 9 cases (reader 2) and 7 cases (reader 3)
  • Many cases classified as partial response or stable disease by modified RECIST would have been classified as stable disease or progressive disease by volumetry
• The authors' conclusion: The authors concluded that tumour volumetry is a reproducible and reliable method for showing small tumour changes, with higher agreement between readers than modified RECIST. They stated they would prospectively validate volumetric response criteria against survival.
• Limitations the authors state:
  • Only a small number of patients could be included, because all image data had to be available digitally
  • Because of the small numbers, the study could not set reference standards for volumetric response categories
  • Different CT techniques were used (with or without contrast and with different delays). The authors said this did not influence the results but did require extra manual work.
  • Volumetry was more time consuming, needing 10 to 15 minutes per reading

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, Chemotherapy, Modified RECIST (mRECIST).

Related studies

• Induction Therapy for Mesothelioma — I. Opitz, W. Weder (2015)
• A New Prognostic Score Supporting Treatment Allocation for Multimodality Therapy for Malignant Pleural Mesothelioma: A Review of 12 Years' Experience — I. Opitz, M. Friess, et al. (2015)
• Integrated positron emission tomography-computed tomography does not accurately stage intrathoracic disease of patients undergoing trimodality therapy for malignant pleural mesothelioma — J. Pilling, J.A. Dartnell, et al. (2010)
• P-32 bremsstrahlung SPECT helps assess intracavitary therapy — B. Petri, R. Nance, et al. (1992)
• Role of integrated 18-fluorodeoxyglucose position emission tomography-computed tomography in patients surveillance after multimodality therapy of malignant pleural mesothelioma — C. Tan, S. Barrington, et al. (2010)
• The toxicological response of Brazilian chrysotile asbestos: a multidose subchronic 90-day inhalation toxicology study with 92-day recovery to assess cellular and pathological response — D.M. Bernstein, R. Rogers, et al. (2006)

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