Abstract
The aim of this study was to evaluate the role of metabolic parameters analyzed at baseline and at interim FDG‐PET in predicting disease outcome in unresectable MPM patients receiving pemetrexed‐based chemotherapy. A consecutive series of MPM patients treated between February 2004 and July 2013 with first‐line pemetrexed‐based chemotherapy, and evaluated by FDG‐PET and CT scan at baseline and after two cycles of chemotherapy, was reviewed. Best CT scan response was assessed according to modified RECIST criteria. Progression‐free survival (PFS) and overall survival (OS) were correlated with FDG‐PET parameters, such as maximum standardized uptake value (SUVmax), total lesion glycolysis (TLG), and percentage changes in SUVmax (∆SUV) and TLG (∆TLG). Overall, 142 patients were enrolled; 77 (54%) received talc pleurodesis before chemotherapy. Baseline SUVmax and TLG showed a statistically significant correlation with PFS and OS (P < 0.05) in both group of patients (treated and untreated with pleurodesis). In 65 patients not receiving pleurodesis, SUVmax reduction ≥25% (∆SUV ≥ 25%) and TLG reduction ≥30% (∆TLG ≥ 30%) were significantly associated with longer PFS (P < 0.05). Patients showing both ∆SUV ≥ 25% and ∆TLG ≥ 30% responses had a significant reduction in the risk of disease progression (HR:0.31, P < 0.001) and death (HR:0.52, P = 0.044). Neither ∆SUV nor ∆TLG showed similar association with survival outcomes in patients treated with pleurodesis. Our study confirmed the prognostic role of baseline FDG‐PET in a large series of MPM patients treated with first‐line pemetrexed‐based chemotherapy. Moreover, use of ∆SUV ≥ 25% and ∆TLG ≥ 30% as cut‐off values to define early metabolic response supported the role of FDG‐PET in predicting disease outcome and treatment response in patients not receiving pleurodesis.
Highlights
Malignant pleural mesothelioma (MPM) is a rare and mostly fatal tumor, whose incidence is increasing worldwide [1]
Our study confirmed the prognostic role of baseline FDG-P ET in a large series of MPM patients treated with first-line pemetrexed-based chemotherapy
Like all computed tomography (CT) criteria, they do not take into account the viability of tumor tissue, which can be better assessed with a functional imaging technique such as [18F]fluorodeoxyglucose positron emission tomography (FDG-PET) [3, 6]
Summary
Malignant pleural mesothelioma (MPM) is a rare and mostly fatal tumor, whose incidence is increasing worldwide [1]. Proper definition of baseline prognostic characteristics and reliable assessment of response to therapy are important components of patient care in everyday practice as well as in clinical trials. Tumor assessment and response evaluation with conventional criteria based on contrast-enhanced computed tomography (CT) measurements are challenging in MPM, because of its diffuse pattern of growth. Modified RECIST criteria have been implemented and are considered the reference standard in clinical practice and ongoing trials. They have a high interobserver variability and were not supported by theoretical studies on modeling of mesothelioma growth [2,3,4,5]. Like all CT criteria, they do not take into account the viability of tumor tissue, which can be better assessed with a functional imaging technique such as [18F]fluorodeoxyglucose positron emission tomography (FDG-PET) [3, 6]
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