FDG PET/CT patterns of treatment failure of malignant pleural mesothelioma: relationship to histologic type, treatment algorithm, and survival

Our plain-English summary of FDG PET/CT patterns of treatment failure of malignant pleural mesothelioma: relationship to histologic type, treatment algorithm, and survival, by V.H. Gerbaudo, M. Mamede, B. Trotman-Dickenson, et al (European Journal of Nuclear Medicine and Molecular Imaging, 2011).

The study

• Authors: V.H. Gerbaudo, M. Mamede, B. Trotman-Dickenson, H. Hatabu, D.J. Sugarbaker
• Journal: European Journal of Nuclear Medicine and Molecular Imaging
• Published: 2011;38(5):810-21
• Cited by: 40 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Purpose: This study investigated the diagnostic performance and prognostic value of fluorodeoxyglucose (FDG) positron emission tomography (PET)/CT in suspected malignant pleural mesothelioma (MPM) recurrence, in the context of patterns and intensity of FDG uptake, histologic type, and treatment algorithm.

Methods: Fifty patients with MPM underwent FDG PET/CT for restaging 11 ± 6 months after therapy. Tumor relapse was confirmed by histopathology, and by clinical evolution and subsequent imaging. Progression-free survival was defined as the time between treatment and the earliest clinical evidence of recurrence. Survival after FDG PET/CT was defined as the time between the scan and death or last follow-up. Overall survival was defined as the time between initial treatment and death or last follow-up date.

Results: Treatment failure was confirmed in 42 patients (30 epithelial and 12 non-epithelial MPM). Sensitivity, specificity, accuracy, negative predictive value, and positive predictive value for FDG PET/CT were 97.6, 75, 94, 86, and 95.3%, respectively. FDG PET/CT evidence of single site of recurrence was observed in the ipsilateral hemithorax in 18 patients (44%), contralaterally in 2 (5%), and in the abdomen in 1 patient (2%). Bilateral thoracic relapse was detected in three patients (7%). Simultaneous recurrence in the ipsilateral hemithorax and abdomen was observed in ten (24%) patients and in seven (17%) in all three cavities. Unsuspected distant metastases were detected in 11 patients (26%). Four patterns of uptake were observed in recurrent disease: focal, linear, mixed (focal/linear), and encasing, with a significant difference between the intensity of uptake in malignant lesions compared to benign post-therapeutic changes. Lesion uptake was lower in patients previously treated with more aggressive therapy and higher in intrathoracic lesions of patients with distant metastases. FDG PET/CT helped in the selection of 12 patients (29%) who benefited from additional previously unplanned treatment at the time of failure. Multivariate analysis showed that histologic type remained the only independent predictor of progression-free survival. Survival after relapse was independently predicted by the pattern of FDG uptake and PET nodal status, and overall survival by the maximum standard uptake value.

Conclusion: FDG PET/CT is an accurate modality to diagnose and to estimate the extent of locoregional and distant MPM recurrence, and it carries independent prognostic value. Once the disease recurs, survival outcomes seem to be independent of histologic type and highly dependent on the intensity of lesion uptake and on the pattern of metabolically active disease in FDG PET/CT. Our observations should be considered limited to patients treated surgically with or without perioperative therapies and should not be extrapolated to those unresectable cases treated with chemotherapy alone.

In plain English

This study tested whether FDG PET/CT could detect returning malignant pleural mesothelioma and predict survival. Patients were injected with a tracer, fluorodeoxyglucose (FDG); PET measured its uptake and CT showed anatomy. Fifty consecutive patients with suspected recurrence, all previously treated with surgery (pleurectomy/decortication or extrapleural pneumonectomy), were scanned. The article does not discuss asbestos exposure. Recurrence was confirmed in 42 and excluded in 8. The scans were true-positive in 41, true-negative in 6, false-positive in 2 and false-negative in 1. Sensitivity was 97.6% (95% confidence interval 86–99%). Specificity, based on the 8 patients without recurrence, was 75% (95% confidence interval 36–99%). The scans found unsuspected distant spread in 11 of the 42 recurrent cases (26%). On average, recurrences took up more tracer than harmless post-surgical changes, though ranges overlapped. In multivariate analysis, histology (tumor type) was the only independent predictor of time to recurrence. After the scan, the uptake pattern and lymph node findings independently predicted survival. The authors concluded FDG PET/CT is accurate for diagnosing recurrence and estimating its extent. They cautioned that their findings apply only to patients treated with surgery.

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: Single-institution study of the diagnostic accuracy and prognostic value of FDG PET/CT imaging in consecutive patients with suspected recurrence of malignant pleural mesothelioma. Patients were injected intravenously with FDG and scanned on a combined PET/CT scanner. The PET images were used to measure tracer uptake (standard uptake values), and the CT scans were used for attenuation correction and anatomic coregistration.
• Who was studied: 50 consecutive patients (34 men, 16 women, median age 62) with histologically confirmed malignant pleural mesothelioma (37 epithelial, 13 non-epithelial), scanned for restaging between October 2003 and December 2005
• Exposure: Asbestos exposure is not reported. The study examined FDG PET/CT findings after previous surgical treatment: pleurectomy/decortication (23 patients) or extrapleural pneumonectomy (27 patients), with or without chemotherapy and radiotherapy.
• Main results:
  • Treatment failure (recurrence) was confirmed in 42 of the 50 patients (84%)
  • In 8 patients, recurrence was excluded by follow-up
  • Among the 50 patients, FDG PET/CT was true-positive in 41, true-negative in 6, false-positive in 2 and false-negative in 1
  • Sensitivity was 97.6% (95% CI 86–99%), specificity 75% (95% CI 36–99%), accuracy 94% (95% CI 87–99%), negative predictive value 86% and positive predictive value 95.3%
  • Recurrence was at a single site in the same-side chest in 18 patients (44%), the opposite-side chest in 2 (5%), and the abdomen in 1 (2%)
  • FDG PET/CT showed unsuspected distant metastases in 11 of the 42 patients with confirmed recurrence (26%), with 20 lesions in total
  • Same-side recurrence was more common after pleurectomy/decortication (59%) than after extrapleural pneumonectomy (30%). Distant relapse was more common after extrapleural pneumonectomy (35%) than after pleurectomy/decortication (18.2%) (p=0.04).
  • Average tracer uptake (SUVmax) was 11.27 plus or minus 4.76 (range 2 to 22.7) in malignant lesions (n=42), compared with 3.28 plus or minus 1.67 (range 2.1 to 6.96) in benign post-surgical changes in relapse-free patients (n=8); p=0.0001. The ranges overlapped.
  • Uptake in chest lesions was higher in patients with distant metastases (SUVmax 15.4, n=11) than in patients without them (8.59, n=31); p=0.0001
  • Median progression-free survival among the 50 patients was 6.5 months
  • In multivariate analysis, histologic type was the only independent predictor of progression-free survival (relative risk 9.42; p=0.047). Median progression-free survival was 10 months for epithelial and 4 months for non-epithelial tumors.
  • Median survival after relapse was 6 months
  • The only independent predictors of survival after the restaging scan were the PET pattern of uptake in the chest (relative risk 2.34; p=0.01) and PET lymph node status (relative risk 2.26; p=0.05)
  • Median overall survival among 49 patients was 21 months
  • Lesion SUVmax at initial staging was the only independent predictor of overall survival (relative risk 7.78; p=0.017)
  • FDG PET/CT changed management in 12 patients (29%) with confirmed recurrence by starting previously unplanned treatment
  • These 12 patients had a median survival after relapse of 13 months, compared with 6 months for the 30 patients who recurred but received no additional treatment. The difference was not statistically significant (p=0.26).
• The authors' conclusion: The authors concluded that FDG PET/CT is accurate for diagnosing and estimating the extent of local and distant recurrence of malignant pleural mesothelioma, and that it carries independent prognostic value
• Limitations the authors state:
  • Follow-up intervals varied, which could have biased the progression-free survival estimates
  • The findings apply only to surgically treated patients and should not be extended to patients whose tumors could not be removed and who received chemotherapy alone
  • There is no well-defined, accepted size criterion for judging lymph node disease in this cancer on imaging
  • The results on changes to management are preliminary and need prospective confirmation in larger series

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, Histopathology, Progression-Free Survival, Overall Survival, Hemithorax, Bilateral, Intrathoracic, Multivariate Analysis.

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