A Novel Prognostic Model for Malignant Mesothelioma Incorporating Quantitative FDG-PET Imaging with Clinical Parameters

Abstract

Purpose: Existing prognostic systems for malignant pleural mesothelioma do not incorporate imaging information. We aimed to identify the contribution of quantitative fluorodeoxyglucose positron emission tomography (FDG-PET) analysis to other prognostic variables in this disease.Experimental Design: Patients with malignant pleural mesothelioma underwent helical thoracoabdominal computed tomography and FDG-PET scans at baseline. Patients were treated as clinically indicated and followed for survival. FDG-PET variables derived included total glycolytic volume, a composite of tumor volume and glycolytic activity.Results: Ninety-three patients were accrued from 2003 to 2006. Of 89 eligible assessable patients, 28 had undergone pleurodesis before enrolment. Seventeen patients remained alive at analysis; median survival is 15.4 months. On univariate analysis, significant prognostic factors were: total glycolytic volume on FDG-PET (P = 0.003), sarcomatoid histology (P < 0.0005), weight loss (P = 0.031), computed tomography stage (P = 0.015), and European Organization for Research and Treatment of Cancer good prognostic score (P = 0.049). In patients with epithelioid or biphasic histology, baseline total glycolytic volume remained predictive of survival in patients with (P = 0.01) or without (P = 0.018) previous pleurodesis. In multivariate analysis, no variable other than histology contributed to the model in patients with sarcomatoid histology; total glycolytic volume and weight loss contributed to the models in patients with nonsarcomatoid histology. computed tomography-assessed tumor-node-metastasis stage did not contribute to the model. A nomogram, which incorporates quantitative PET parameters and pleurodesis into prognostic information, is presented.Conclusions: Sarcomatoid histology remains the strongest prognostic factor. In patients with non sarcomatoid disease, volumetric FDG-PET parameters are more predictive of survival than tumor-node-metastasis staging, suggesting that tumor volume and glycolytic activity may be more important determinants of prognosis in malignant pleural mesothelioma than anatomic extent of disease.

Volumetric assessment in malignant pleural mesothelioma

“…Therefore, there is a greater emphasis on determining resectability rather than an attempt at clinical staging in these patients. If deemed unresectable, serial imaging with CT or PETCT to determine response to therapy by comparing differences in uptake and tumor measurements is often done (21)(22)(23)(24)(25).…”

“…The European Organization for Research and Treatment of Cancer (EORTC) (32) and the Cancer and Leukemia Group B (CALGB) (33) have identified several prognostic factors from pooled cohorts of patients treated on chemotherapy trials prospectively; worse prognosis was associated with poor performance status, non-epithelial histology, advanced stage (stage IV), gender, age and anemia, along with metabolic activity and tumor volume (22,30,34,35).…”

“…Other modalities, such as MRI (24) and 18 F-FDG PET/ CT (22,36,44) have been successfully used to measure tumor volume in MPM ( Table 1). For MRI, tumor segmentation has been performed using a HASTE (halfFourier single-shot fast spin-echo) sequence, but this can be limited by signal inhomogeneity and motion artifacts, with a segmentation time of 10 minutes described per patient (45).…”

“…For MRI, tumor segmentation has been performed using a HASTE (halfFourier single-shot fast spin-echo) sequence, but this can be limited by signal inhomogeneity and motion artifacts, with a segmentation time of 10 minutes described per patient (45). Tumor segmentation on PET/CT allows calculation of the volume of metabolically active tumor by segmenting the volume of interest using an adaptive threshold based on SUV (22,23,38,44). The total glycolytic volume (TGV) is a measure of tumor volume and metabolic activity, with a correlation between TGV and tumor activity (46).…”

“…Measurement of the volume of metabolically active tumor on 18 F-FDG PET/CT was incorporated into a prognostic model, incorporating both tumor volume and glycolysis, termed TGV (22,38). SUV alone did not significantly predict survival, suggesting that tumor volume provides the main prognostic information (22). …”