Quantitative analyses at baseline and interim PET evaluation for response assessment and outcome definition in patients with malignant pleural mesothelioma

Our plain-English summary of Quantitative analyses at baseline and interim PET evaluation for response assessment and outcome definition in patients with malignant pleural mesothelioma, by E. Lopci, P.A. Zucali, G.L. Ceresoli, et al (European Journal of Nuclear Medicine and Molecular Imaging, 2015).

The study

• Authors: E. Lopci, P.A. Zucali, G.L. Ceresoli, M. Perrino, L. Giordano, L. Gianoncelli, E. Lorenzi, M. Gemelli, A. Santoro, A. Chiti
• Journal: European Journal of Nuclear Medicine and Molecular Imaging
• Published: 2015;42(5):667-75
• Cited by: 34 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Purpose: Quantitative analyses on FDG PET for response assessment are increasingly used in clinical studies, particularly with respect to tumours in which radiological assessment is challenging and complete metabolic response is rarely achieved after treatment. A typical example is malignant pleural mesothelioma (MPM), an aggressive tumour originating from mesothelial cells of the pleura. We present our results concerning the use of semiquantitative and quantitative parameters, evaluated at the baseline and interim PET examinations, for the prediction of treatment response and disease outcome in patients with MPM.

Methods: We retrospectively analysed data derived from 131 patients (88 men, 43 women; mean age 66 years) with MPM who were referred to our institution for treatment between May 2004 and July 2013. Patients were investigated using FDG PET at baseline and after two cycles of pemetrexed-based chemotherapy. Responses were determined using modified RECIST criteria based on the best CT response after treatment. Disease control rate, progression-free survival (PFS) and overall survival (OS) were calculated for the whole population and were correlated with semiquantitative and quantitative parameters evaluated at the baseline and interim PET examinations; these included SUVmax, total lesion glycolysis (TLG), percentage change in SUVmax (ΔSUVmax) and percentage change in TLG (ΔTLG).

Results: Disease control was achieved in 84.7 % of the patients, and median PFS and OS for the entire cohort were 7.2 and 14.3 months, respectively. The log-rank test showed a statistically significant difference in PFS between patients with radiological progression and those with partial response (PR) or stable disease (SD) (1.8 vs. 8.6 months, p < 0.001). Baseline SUVmax and TLG showed a statistically significant correlation with PFS and OS (p < 0.001). In the entire population, both ΔSUVmax and ΔTLG were correlated with disease control based on best CT response (p < 0.001). ΔSUVmax was significantly correlated with PFS in the entire population (p = 0.02) and with both PFS and OS in patients not undergoing talc pleurodesis (n = 65; p < 0.01 for PFS, p = 0.03 for OS), and in patients without pleurodesis presenting a SD and/or PR at CT after two cycles.

Conclusion: These results confirm the role of FDG PET in the assessment of disease prognosis and treatment efficacy in MPM patients receiving first-line pemetrexed-based chemotherapy. In particular, metabolic response evaluated using ΔSUVmax can be used to predict outcome in MPM patients not undergoing talc pleurodesis who achieve SD and/or PR at the interim CT evaluation.

In plain English

This retrospective study reviewed 131 consecutive patients with malignant pleural mesothelioma who were referred to one institution in Italy between May 2004 and July 2013. Patients were not candidates for surgery. All received pemetrexed-based chemotherapy and had FDG PET scans, which show how actively tumours take up sugar, before treatment and after two cycles. The study did not examine asbestos exposure. For the whole group, median progression-free survival was 7.2 months and median overall survival was 14.3 months. Disease was controlled in 84.7% of patients. Two readings from the first scan were statistically linked with progression-free and overall survival: peak tumour activity (SUVmax) and total lesion glycolysis (TLG), a measure combining active tumour volume and activity. Among the 65 patients who had not had talc pleurodesis, the percentage change in SUVmax between the two scans was linked with progression-free survival (p=0.002) and overall survival (p=0.028). This link also held in the 51 such patients whose CT after two cycles showed stable disease or partial response. The authors concluded that this PET change can help predict outcome in those patients. They analysed patients without pleurodesis separately because pleurodesis could have influenced the PET changes.

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 patients treated at a single institution, comparing PET measurements with CT response and survival
• Who was studied: 131 consecutive patients with malignant pleural mesothelioma (88 men, 43 women; mean age 66), not candidates for surgery, referred to the authors' institution in Italy between May 2004 and July 2013, each with FDG PET at baseline and after two chemotherapy cycles
• Exposure: Asbestos exposure was not assessed. The treatment studied was first-line pemetrexed-based chemotherapy: pemetrexed with carboplatin (100 patients), pemetrexed alone (3 patients), or pemetrexed and carboplatin with bevacizumab (28 patients). It was monitored by FDG PET and CT.
• Main results:
  • In the whole cohort, median progression-free survival was 7.2 months and median overall survival was 14.3 months. The disease control rate was 84.7%.
  • Patients with radiological progression had shorter progression-free survival than those with partial response or stable disease (1.8 vs. 8.6 months; p<0.001). Overall survival showed a similar pattern (8.7 vs. 19.2 months; p<0.001).
  • Baseline SUVmax (median 7.1) and baseline TLG (median 400.3) were each significantly correlated with progression-free and overall survival in the whole population (p<0.001).
  • In multivariate analysis, the independent prognostic factors for progression-free survival were ECOG performance status (p=0.004) and TLG (p<0.001). For overall survival they were histology (p=0.002), ECOG performance status (p=0.019), SUVmax (p=0.033) and TLG (p=0.008).
  • CT after two cycles showed partial response in 39 of 124 evaluable patients (31.5%), stable disease in 69 (55.6%) and progressive disease in 16 (12.9%).
  • Both PET change measures were associated with best CT response (p<0.001). Median change in SUVmax was −13.5% in patients with disease control and 33.2% in those with progression. Median change in TLG was −47% and 92.6% in the same two groups.
  • In the 65 patients without talc pleurodesis, change in SUVmax was significantly correlated with progression-free survival (p=0.002) and overall survival (p=0.028). Change in TLG was predictive of progression-free survival (p=0.002) but not overall survival.
  • Among patients without pleurodesis, change in SUVmax correlated with progression-free survival (p=0.05) and overall survival (p=0.05) in the 29 with stable disease on interim CT. It also correlated with both (p=0.009 and p=0.007) in the 51 with stable disease or partial response. Change in TLG was not correlated with either outcome in these subgroups.
• The authors' conclusion: The authors concluded that, compared with CT response by modified RECIST alone, PET metabolic response adds value by predicting outcome in patients without talc pleurodesis who show stable disease and/or partial response on CT after two cycles of chemotherapy.
• Limitations the authors state:
  • Talc pleurodesis could have influenced the PET change measures, so the authors analysed patients without pleurodesis separately.
  • Interim CT response could not be obtained retrospectively for seven patients.

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, Mesothelial Cells, Pleura, Pemetrexed (Alimta), Chemotherapy, Modified RECIST (mRECIST), Progression-Free Survival, Overall Survival.

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