FDG PET-derived parameters as prognostic tool in progressive malignant pleural mesothelioma treated patients

Our plain-English summary of FDG PET-derived parameters as prognostic tool in progressive malignant pleural mesothelioma treated patients, by E. Incerti, S. Broggi, A. Fodor, et al (European Journal of Nuclear Medicine and Molecular Imaging, 2018).

The study

• Authors: E. Incerti, S. Broggi, A. Fodor, M. Cuzzocrea, A.M. Samanes Gajate, P. Mapelli, C. Fiorino, I. Dell'Oca, M. Pasetti, M. Cattaneo, R. Calandrino, L. Gianolli, N. Di Muzio, M. Picchio
• Journal: European Journal of Nuclear Medicine and Molecular Imaging
• Published: 2018;45(12):2071-2078
• Cited by: 7 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Purpose: The value of FDG PET-derived parameters in predicting overall survival (OS), local relapse-free survival (LRFS) and distant relapse-free survival (DRFS) in treated patients with malignant pleural mesothelioma (MPM) was evaluated.

Methods: This retrospective evaluation included 55 MPM patients treated between March 2006 and February 2015 with FDG PET/CT-guided salvage helical tomotherapy (HTT) after previous surgery plus chemotherapy. Univariate Cox regression analysis was performed to assess the impact of the following FDG PET-derived parameters: biological target volume (BTV), mean and maximum standardized uptake values (SUVmean/max), metabolic tumour volume (MTV) and total lesion glycolysis (TLG), measured using different uptake thresholds (40%, 50% and 60%). Logistic regression was then performed to identify the best FDG PET-derived parameters for selecting patients with poorer survival.

Results: The median OS was 9.1 months (range 0.0 - 69.6 months) after the end of HTT; 54/55 patients were dead at the last follow-up. BTV and TLG40, TLG50 and TLG60 were the most significant predictors of OS (p < 0.005). The median OS was 4.8 months in patients with MTV60 >5 cm3 and TLG40 >334.4, compared with 13.8 months and 16.1 months in patients with smaller values, respectively. The median LRFS and DRFS were 6.2 months (range 1.2 - 39.4 months) and 6.5 months (0.0 - 66.4 months), respectively. TLG40, TLG50 and TLG60 were significantly correlated with LRFS (p < 0.015). Median DRFS was 6.4 months in patients with MTV40 >39.6 cm3 and 6.2 months in patients with TLG40 >334.4, compared with 17 months and 18.8 months in patients with smaller values. BTV, TLG40 and MTV40 were also found to be good predictors in patients with poor OS/LRFS/DRFS (median survival times less than the median values).

Conclusion: FDG PET-derived parameters effectively discriminated patients with a poor prognosis and may be helpful in the selection of MPM patients for salvage HTT.

In plain English

This retrospective study from Milan, Italy, looked at 55 patients with malignant pleural mesothelioma that had progressed or relapsed after surgery and/or chemotherapy. They were treated between March 2006 and February 2015 with PET/CT-guided salvage helical tomotherapy, a type of radiotherapy. The authors tested whether measurements from FDG PET scans taken before treatment, mainly of tumour volume and total metabolic activity, predicted survival. The study did not examine asbestos exposure. Median overall survival after treatment was 9.1 months, and 54 of the 55 patients had died by the last follow-up. Patients with higher values did worse. Median overall survival was 4.8 months when MTV60 was above 5 cm3, against 13.8 months below it. It was 4.8 months when TLG40 was above 334.4, against 16.1 months below it. Similar differences were seen for distant relapse. Uptake-only measures (SUVmean and SUVmax) were not significantly linked to overall or local relapse-free survival. The authors concluded that these measures were associated with survival and may help identify patients not eligible for salvage radiotherapy. They said prospective evaluation is required and noted that the study was retrospective and small.

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 treated patients (single institution), using Cox regression and logistic regression to test PET scan measurements as predictors of survival
• Who was studied: 55 patients with histologically confirmed malignant pleural mesothelioma that had progressed or relapsed after previous surgery and/or chemotherapy, treated with FDG PET/CT-guided helical tomotherapy at IRCCS San Raffaele Scientific Institute, Milan, between March 2006 and February 2015
• Exposure: Not an asbestos exposure study. The factors studied were FDG PET-derived measurements (BTV, SUVmean, SUVmax, MTV and TLG at 40%, 50% and 60% thresholds) taken before salvage helical tomotherapy. The pleura received a median dose of 56 Gy.
• Main results:
  • Across all 55 patients, median overall survival after the end of tomotherapy was 9.1 months (range 0.0 to 69.6 months). 54 of 55 patients had died by the last follow-up.
  • Median overall survival was 4.8 months in patients with MTV60 above 5 cm3 versus 13.8 months in those below. The Cox risk ratio was 2.07 (1.16 to 3.70), p = 0.015.
  • Median overall survival was 4.8 months in patients with TLG40 above 334.4 versus 16.1 months in those below. The Cox risk ratio was 2.37 (1.31 to 4.28), p = 0.005.
  • Median distant relapse-free survival was 6.5 months, with 33 of 55 patients having an event. It was 6.4 months with MTV40 above 39.6 cm3 (risk ratio 3.19, 1.48 to 6.88) and 6.2 months with TLG40 above 334.4 (risk ratio 3.44, 1.58 to 7.52). In patients below these values it was 17 months and 18.8 months respectively.
  • For local relapse-free survival (median 6.2 months; 22 of 55 events), only TLG at all thresholds, analysed as a continuous measure, was significantly correlated (p less than 0.015). No correlation was found when the median was used as the cut-off.
  • Neither overall survival nor local relapse-free survival was significantly correlated with SUVmean or SUVmax.
  • In logistic regression, median BTV, MTV40 and TLG40 values showed the best correlations with worse prognosis, defined as survival below the median. For overall survival, BTV above 214.1 cm3 had a risk ratio of 5.77 (1.72 to 19.28), p = 0.004.
• The authors' conclusion: The authors concluded that FDG PET-derived volume parameters showed significant associations with survival in MPM patients treated with salvage helical tomotherapy. They said these parameters may help identify patients with a poor prognosis who are therefore not eligible for salvage radiotherapy, and that prospective evaluation is required.
• Limitations the authors state:
  • The authors stated the study was limited by its retrospective nature and the small number of patients, who were those selected for a "radical" palliative therapy.
  • The authors noted that treatment strategies for MPM may have changed since the first patients in the study were treated.

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, Chemotherapy, Median Survival, Prognosis.

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