Clinical utility of FDG-PET/CT for post-surgery surveillance of malignant pleural mesothelioma - Comparison with contrast-enhanced CT

Our plain-English summary of Clinical utility of FDG-PET/CT for post-surgery surveillance of malignant pleural mesothelioma - Comparison with contrast-enhanced CT, by K. Kitajima, M. Hashimoto, T. Katsuura, et al (Oncotarget, 2019).

The study

• Authors: K. Kitajima, M. Hashimoto, T. Katsuura, N. Kondo, T. Minami, K. Kuribayashi, S. Hasegawa, T. Kijima, K. Yamakado
• Journal: Oncotarget
• Published: 2019;10(63):6816-6828
• Cited by: 9 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Objectives: To assess the diagnostic accuracy of fluorodeoxyglucose (FDG)-positron emission tomography/computed tomography (PET/CT) findings for recurrent malignant pleural mesothelioma (MPM) after a radical surgery procedure and their impact on clinical management in comparison with contrast-enhanced CT.

Results: Treatment failure was confirmed in 40 patients. The patient-based area under the receiver-operating characteristic (ROC) curves (AUC)/sensitivity/specificity/accuracy were 0.915/90.0%/80.0%/88.0% for FDG-PET/CT, and 0.805/75.0%/90.0%/78.0% for contrast-enhanced CT, respectively. AUC and sensitivity values were significantly different between the modalities (both p=0.041). Patient-based AUC values for diagnosing locoregional recurrence (ipsilateral hemithoracic recurrence) and distant metastasis, including peritoneal dissemination and lung, bone, muscle, and liver metastasis, were also significantly different (p=0.023 and p=0.035, respectively). The findings of FDG-PET/CT resulted in a change of management for 14 of the 50 patients (28%) by initiating new treatment. Of six patients judged as not having recurrence by contrast-enhanced CT but truly having recurrence based on FDG-PET/CT findings, 4 patients received new treatment due toFDG-PET/CT.

Methods: Fifty patients who underwent radical surgery for MPM received FDG-PET/CT and contrast-enhanced neck/chest/abdomen/pelvis CT examinations for surveillance or suspected recurrence within a 2-week period. Diagnostic ability was determined on a patient and lesion-site basis by 2 experienced examiners, and the modalities were compared using ROC analysis and McNemar test results. Lesion status was determined on the basis of histopathology, radiological imaging and clinical follow-up for longer than 6 months.

Conclusion: FDG-PET/CT findings were shown to be more accurate for assessing MPM recurrence and more often led to therapy change than contrast-enhanced CT.

Copyright: © 2019 Kitajima et al.

In plain English

This retrospective Japanese study compared FDG-PET/CT with contrast-enhanced CT, performed within 2 weeks of each other, for detecting returning malignant pleural mesothelioma in 50 patients after radical surgery (extrapleural pneumonectomy in 29, pleurectomy/decortication in 21). The article does not report on asbestos exposure. Recurrence was confirmed in 40. FDG-PET/CT detected 36 of them (sensitivity 90.0%, 95% confidence interval 80.7 to 99.3); its area under the curve (AUC) was 0.915 (0.795 to 0.968). Contrast-enhanced CT detected 30 (75.0%, 61.6 to 88.4), with an AUC of 0.805 (0.668 to 0.895). Both differences were statistically significant. Among the 10 patients without recurrence, specificity was 80.0% (8/10; 55.2 to 100) for FDG-PET/CT and 90.0% (9/10; 71.4 to 100) for CT. FDG-PET/CT also did significantly better for same-side chest recurrence and, by AUC, distant spread. Differences for bone and muscle metastasis were not significant; within surgery groups, only the chest-recurrence AUC after extrapleural pneumonectomy differed significantly. FDG-PET/CT findings led to new treatment for 14 patients. The authors concluded FDG-PET/CT was superior for assessing recurrence; they cited the small, single-institution, retrospective design as a limitation.

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, single-institution study comparing the diagnostic accuracy of FDG-PET/CT with contrast-enhanced CT. Two-reader consensus readings were checked against biopsy, cytology or at least 6 months of follow-up.
• Who was studied: 50 patients (40 male, 10 female; mean age 62.5, range 37-73), chosen from 149 who had radical surgery for malignant pleural mesothelioma at Hyogo College of Medicine, Japan, between May 2006 and December 2017. Surgery was extrapleural pneumonectomy in 29 and pleurectomy/decortication in 21. Tumors were epithelial in 46. Each patient had both scans within 2 weeks of each other.
• Exposure: This is not an asbestos exposure study, and the article does not report the patients' asbestos exposure. The study compared two imaging methods, FDG-PET/CT and contrast-enhanced CT, used to detect recurrence after surgery.
• Main results:
  • Treatment failure (recurrence) was confirmed in 40 of the 50 patients.
  • In all 50 patients, FDG-PET/CT had an AUC of 0.915, sensitivity of 90.0% (36/40), specificity of 80.0% (8/10), PPV of 94.7% (36/38), NPV of 66.7% (8/12) and accuracy of 88.0% (44/50).
  • The 95% confidence intervals for FDG-PET/CT in all patients were: AUC 0.795 to 0.968, sensitivity 80.7 to 99.3, specificity 55.2 to 100, PPV 87.6 to 100, NPV 40.0 to 93.3, and accuracy 79.0 to 97.0.
  • In all 50 patients, contrast-enhanced CT had an AUC of 0.805, sensitivity of 75.0% (30/40), specificity of 90.0% (9/10), PPV of 96.8% (30/31), NPV of 47.4% (9/19) and accuracy of 78.0% (39/50).
  • The 95% confidence intervals for contrast-enhanced CT in all patients were: AUC 0.668 to 0.895, sensitivity 61.6 to 88.4, specificity 71.4 to 100, PPV 90.5 to 100, NPV 24.9 to 69.8, and accuracy 66.5 to 89.5.
  • AUC and sensitivity were significantly higher with FDG-PET/CT than with contrast-enhanced CT (both p=0.041).
  • For ipsilateral hemithoracic (locoregional) recurrence, FDG-PET/CT had significantly higher AUC, sensitivity and accuracy than contrast-enhanced CT. AUC was 0.958 versus 0.838, and sensitivity was 90.9% (30/33) versus 57.6% (19/33). The p values were 0.023, 0.026 and 0.0077.
  • For distant metastasis, the patient-based AUC was 0.957 for FDG-PET/CT and 0.852 for contrast-enhanced CT (p=0.035).
  • Sensitivity for bone and muscle metastasis tended to be higher with FDG-PET/CT, but the difference was not statistically significant.
  • The extrapleural pneumonectomy and pleurectomy/decortication groups were also analyzed separately. For overall recurrence, FDG-PET/CT values were higher in both groups, but not significantly so.
  • Within the surgery groups, the only significant difference was the AUC for thoracic recurrence in the extrapleural pneumonectomy group (p=0.031 in the text; Table 4 prints 0.032).
  • FDG-PET/CT gave 4 false-negative and 2 false-positive results.
  • FDG-PET/CT findings changed management for 14 of the 50 patients (28.0%) by starting new treatment: chemotherapy in 8, radiotherapy in 3, resection in 2 and radiofrequency ablation in 1.
  • Six patients judged free of recurrence on contrast-enhanced CT were shown by FDG-PET/CT to have recurrence. In 4 of these patients, FDG-PET/CT was considered to have influenced additional chemotherapy.
• The authors' conclusion: The authors concluded that FDG-PET/CT was superior to contrast-enhanced CT for assessing mesothelioma recurrence, and that its findings led to a change in therapy more often.
• Limitations the authors state:
  • Relatively few patients were studied, all from a single institution.
  • There may have been patient selection bias because of the retrospective design and strict enrollment criteria.
  • Not all results were confirmed by histology, the gold standard. Many were confirmed by clinical follow-up instead.
  • Images were read by consensus rather than by independent readers with formal interobserver variability.
  • The suggestion that FDG-PET/CT may be more valuable after extrapleural pneumonectomy needs confirmation in a larger prospective, multicenter study.

Topics

Medical terms in this study, explained in our Lexicon: Pleural Mesothelioma, Metastasis, Histopathology.

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