Metabolic response assessment with 18F-FDG-PET/CT is superior to modified RECIST for the evaluation of response to platinum-based doublet chemotherapy in malignant pleural mesothelioma

Our plain-English summary of Metabolic response assessment with 18F-FDG-PET/CT is superior to modified RECIST for the evaluation of response to platinum-based doublet chemotherapy in malignant pleural mesothelioma, by S. Kanemura, K. Kuribayashi, N. Funaguchi, et al (European Journal of Radiology, 2017).

The study

• Authors: S. Kanemura, K. Kuribayashi, N. Funaguchi, E. Shibata, K. Mikami, H. Doi, K. Kitajima, S. Hasegawa, T. Nakano
• Journal: European Journal of Radiology
• Published: 2017;86:92-98
• Cited by: 13 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Purpose: Efficient monitoring of tumor responsiveness to chemotherapy is essential to mitigate high mortality risks and cytotoxic effects of chemotherapeutics. However, there is no consensus on the most suitable diagnostic technique/parameters for assessing response to chemotherapy in malignant pleural mesothelioma (MPM). We compared the tumor responsiveness of MPM patients as assessed using modified RECIST (mRECIST) criteria and integrated 18F-FDG-PET/CT.

Methods: Histologically confirmed MPM patients (N=82) who were treated with three cycles of cisplatin and pemetrexed, or carboplatin and pemetrexed, were included. mRECIST and integrated 18F-FDG-PET/CT were used to evaluate MPM tumor response to chemotherapy. Metabolic non-responders were defined as those with a 25% or greater increase in SUVmax compared with the previous value. Time to progression (TTP) and overall survival (OS) were compared between metabolic-responders and non-responders.

Results: After three cycles of chemotherapy, 62(75.6%) of the patients were classified as having SD, 15 (18%) with partial remission (PR), and 5 (6%) with progressive disease (PD), based on mRECIST criteria. The cumulative median OS was 728.0days (95% confidence interval [CI]: 545.9-910.1) and cumulative median TTP was 365.0days (95% CI: 296.9-433.1). For the 82 patients, the disease control rate was 93.9%, whereas the metabolic response rate was only 71.9% (p<0.001). All PD and PR patients were found to be metabolic responders on 18F-FDG-PET/CT; however, among the 62mRECIST SD patients, 18 (29%) were classified as metabolic non-responders. The median TTP for metabolic responders was 13.7 months, while it was 10.0 months for non-responders(p<0.001). Metabolic responders had a trend toward longer OS, although the difference did not reach statistical significance (metabolic responders:33.9 months; non-responders: 21.6 months; p>0.05).

Conclusion: Several mRECIST-confirmed SD MPM patients may be classified as metabolic non-responders on18F-FDGPET/CT. Metabolic response is significantly correlated with the median TTP, suggesting it should be included in the evaluation of the response to chemotherapy in MPM patients classified as mRECIST SD, to identify non-responders.

Copyright © 2016. Published by Elsevier Ireland Ltd.

In plain English

This retrospective study from Hyogo College of Medicine in Japan looked at 82 patients with malignant pleural mesothelioma treated between January 2007 and January 2015 with pemetrexed plus cisplatin (75 patients) or pemetrexed plus carboplatin (7 patients). After three cycles of chemotherapy, tumor response was judged in two ways: by CT measurements of tumor thickness (modified RECIST) and by PET/CT scans measuring tumor uptake of a glucose tracer (SUVmax). By CT, 15 patients had a partial response, 62 had stable disease and 5 had progressive disease. Of the 62 with stable disease, 18 (29%) were classed on PET/CT as having progressive metabolic disease, defined as a rise in SUVmax of 25% or more or new abnormal uptake in another location. In these stable-disease patients, median time to progression was 13.7 months for PET responders and 10.0 months for PET non-responders (p less than 0.001). Median overall survival was 33.9 versus 21.6 months, a difference that was not statistically significant. The authors concluded that PET/CT assessment correlated better with time to progression than modified RECIST. They called for larger prospective studies. Some figures in the article are inconsistent.

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 analysis of patients at a single institution, comparing two methods of judging response to chemotherapy (modified RECIST on CT versus metabolic response on 18F-FDG-PET/CT)
• Who was studied: 82 patients with histologically confirmed malignant pleural mesothelioma (65 men, 17 women; median age 65, range 37 to 77) treated at Hyogo College of Medicine, Japan, between January 2007 and January 2015. Patients with diabetes or prior pleurodesis were excluded. The survival comparison was limited to the 62 patients classed as stable disease by modified RECIST.
• Exposure: Not an asbestos exposure study. The exposure was chemotherapy: pemetrexed (500 mg/m2) with cisplatin (75 mg/m2) in 75 patients, or pemetrexed with carboplatin (AUC5) in 7 patients, every 3 weeks. Response was assessed after three cycles.
• Main results:
  • By modified RECIST on CT (all 82 patients): 15 (18%) partial response, 62 (76%) stable disease, 5 (6%) progressive disease
  • Progressive metabolic disease on PET/CT was defined as a rise in SUVmax of 25% or more compared with the previous value, or the appearance of abnormal uptake in another location. Patients with this finding were the metabolic non-responders.
  • By PET/CT metabolic response (all 82 patients): 6 (7%) complete metabolic response, 29 (35%) partial metabolic response, 24 (30%) stable metabolic disease, 23 (28%) progressive metabolic disease
  • Of the 62 patients with stable disease by modified RECIST, 18 (29%) had progressive metabolic disease on PET/CT
  • For all 82 patients, the disease control rate by modified RECIST was 93.9%. The metabolic response rate by PET/CT was 71.9% (p = 0.0003).
  • In the survival analysis of the 62 stable-disease patients, cumulative median overall survival was 728.0 days (95% CI 545.9 to 910.1) and cumulative median time to progression was 365.0 days (95% CI 296.9 to 433.1)
  • Median time to progression was 13.7 months for metabolic responders and 10.0 months for metabolic non-responders (p less than 0.001)
  • Median time to progression by PET/CT category: 18.7 months (complete metabolic response), 13.8 months (partial), 13.4 months (stable), 10.0 months (progressive)
  • Metabolic responders tended to have longer overall survival (33.9 months versus 21.6 months for non-responders), but the difference was not statistically significant (p greater than 0.05)
  • The stable-disease group and the metabolic responders did not differ in age, sex, stage, histological type or chemotherapy
• The authors' conclusion: The authors concluded that metabolic response on 18F-FDG-PET/CT correlated better with time to progression than modified RECIST. They found modified RECIST was not as effective in more than 25% of cases. They called for further large-scale multicenter prospective studies to confirm the results.

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: Modified RECIST (mRECIST), Chemotherapy, Pleural Mesothelioma, Cisplatin, Pemetrexed (Alimta), Carboplatin, Overall Survival, confidence interval.

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