The association of 18F-FDG PET/CT parameters with survival in malignant pleural mesothelioma

Our plain-English summary of The association of 18F-FDG PET/CT parameters with survival in malignant pleural mesothelioma, by A. Klabatsa, S. Chicklore, S.F. Barrington, et al (European Journal of Nuclear Medicine and Molecular Imaging, 2014).

The study

• Authors: A. Klabatsa, S. Chicklore, S.F. Barrington, V. Goh, L. Lang-Lazdunski, G.J. Cook
• Journal: European Journal of Nuclear Medicine and Molecular Imaging
• Published: 2014;41(2):276-82
• Cited by: 50 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Purpose: Malignant pleural mesothelioma (MPM) is a disease with poor prognosis despite multimodal therapy but there is variation in survival between patients. Prognostic information is therefore potentially valuable in managing patients, particularly in the context of clinical trials where patients could be stratified according to risk. Therefore we have evaluated the prognostic ability of parameters derived from baseline 2-[(18)F]fluoro-2-deoxy-D-glucose positron emission tomography/computed tomography ((18)F-FDG PET/CT).

Methods: In order to determine the relationships between metabolic activity and prognosis we reviewed all (18)F-FDG PET/CT scans used for pretreatment staging of MPM patients in our institution between January 2005 and December 2011 (n = 60) and measured standardised uptake values (SUV) including mean, maximum and peak values, metabolic tumour volume (MTV) and total lesion glycolysis (TLG). Overall survival (OS) or time to last censor was recorded, as well as histological subtypes.

Results: Median follow-up was 12.7 months (1.9-60.9) and median OS was 14.1 months (1.9-54.9). By univariable analysis histological subtype (p = 0.013), TLG (p = 0.024) and MTV (p = 0.038) were significantly associated with OS and SUVmax was borderline (p = 0.051). On multivariable analysis histological subtype and TLG were associated with OS but at borderline statistical significance (p = 0.060 and 0.058, respectively). No statistically significant differences in any PET parameters were found between the epithelioid and non-epithelioid histological subtypes.

Conclusion: (18)F-FDG PET/CT parameters that take into account functional volume (MTV, TLG) show significant associations with survival in patients with MPM before adjusting for histological subtype and are worthy of further evaluation to determine their ability to stratify patients in clinical trials.

In plain English

This retrospective study asked whether pretreatment PET/CT measurements were linked to survival in malignant pleural mesothelioma. The authors reviewed scans of 60 patients (51 men, mean age 64.8 years) at their London institution, taken up to December 2011. They measured how strongly tumours took up a sugar-based tracer (SUVmax, SUVmean, SUVpeak), active tumour volume (MTV), and total lesion glycolysis (TLG), which combines that volume with average uptake. The study did not examine asbestos exposure. Median survival, counted from the PET scan, was 14.1 months. One at a time, subtype (p = 0.013), TLG (p = 0.024) and MTV (p = 0.038) were significantly associated with survival; SUVmax was borderline (p = 0.051). Epithelioid patients had a hazard ratio of death of 0.43 (95% CI 0.22 to 0.84) versus non-epithelioid patients. When subtype and TLG were analysed together, both associations were only borderline (p = 0.060 and 0.058). The authors concluded that volume-based measures were associated with survival before adjusting for subtype, and that prospective evaluation is required. They noted the retrospective design and small numbers in the less common subtypes.

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 of pretreatment 18F-FDG PET/CT scans, analysed with Cox regression and Kaplan-Meier survival analysis
• Who was studied: 60 patients with malignant pleural mesothelioma (mean age 64.8 years, 51 men) who had whole-body 18F-FDG PET/CT for staging before any therapy at the authors' institution in London. The methods give the period as January 2006 to December 2011, while the abstract says January 2005. Patients with prior pleurodesis were excluded. Subtypes were 31 epithelioid, 13 mixed, 5 sarcomatoid, 2 desmoplastic and 9 unknown.
• Exposure: No asbestos exposure data were reported. The factors studied were PET measurements of tumour tracer uptake (SUVmax, SUVmean, SUVpeak), metabolic tumour volume (MTV), and total lesion glycolysis (TLG, calculated as SUVmean multiplied by MTV), together with histological subtype, age, sex and stage.
• Main results:
  • Overall survival was measured from the date of the PET scan to death.
  • Across all 60 patients, median follow-up was 12.7 months (1.9 to 60.9) and median overall survival was 14.1 months (1.9 to 54.9).
  • In univariable analysis, histological group (p = 0.013), TLG (p = 0.024) and MTV (p = 0.038) were significantly associated with survival times.
  • Age, sex, stage, SUVmean and SUVpeak were not significantly associated with survival. SUVmax was borderline (hazard ratio 1.26, 95% CI 1.00 to 1.58, p = 0.051).
  • Epithelioid patients had a lower risk of death than non-epithelioid patients in univariable analysis (hazard ratio 0.43, 95% CI 0.22 to 0.84). The authors described this as less than half the risk at any time.
  • In the multivariable model, histological group (epithelioid hazard ratio 0.53, 95% CI 0.28 to 1.03) and TLG (hazard ratio 1.25, 95% CI 0.99 to 1.51) were associated with survival only at borderline significance (p = 0.060 and 0.058).
  • In Kaplan-Meier analysis, median survival was 8.3 months for non-epithelioid patients versus 22.0 months for epithelioid patients (p = 0.01). It was 11.1 months for patients with SUVmax above 6.3 versus 46.6 months for those at or below that level (p = 0.004).
  • Median survival was 6.4 months for patients with MTV above 755 ml versus 14.4 months for those below (p = 0.001). It was 6.4 months for patients with TLG above 2,914 versus 18.1 months for those below (p = 0.0002).
  • None of the PET measurements differed significantly between epithelioid and non-epithelioid tumours.
• The authors' conclusion: The authors concluded that PET/CT measures that take functional tumour volume into account (MTV, TLG) showed significant associations with survival before adjusting for histological subtype. They said prospective evaluation is required, but that PET parameters show promise for stratifying patients in clinical trials.
• Limitations the authors state:
  • The study was retrospective, and the patient group included people selected for both radical and palliative treatment.
  • Patients with prior pleurodesis were excluded, so the effect of previous pleurodesis on the PET measurements could not be assessed.
  • Treatment approaches may have changed during the study period. The authors judged it unlikely that this biased the results.
  • Subtypes other than epithelioid had too few patients for meaningful comparison, and histology was missing in nine cases.

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, Prognosis, Multimodal Therapy, Clinical Trial, CT Scan, Staging, Overall Survival, Histological Subtype.

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• 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)
• ¹⁸F-fluorodeoxyglucose PET/CT findings in pleural effusions of patients with known cancer. A cytopathological correlation — I. Letovanec, G. Allenbach, et al. (2012)
• Pseudomesotheliomatous lung cancer mimicking mesothelioma on ¹⁸F-FDG PET/CT images: report of 2 cases — T. Nakamori, S. Kosuda, et al. (2013)
• Whole-Body MRI: Comparison of Its Capability for TNM Staging of Malignant Pleural Mesothelioma With That of Coregistered PET/MRI, Integrated FDG PET/CT, and Conventional Imaging — Y. Ohno, M. Yui, et al. (2019)

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