18FDG PET/CT in malignant pleural mesothelioma

Objectives The management of MPM represents one of the most challenging issues in oncology. Our retrospective study aims to evaluate the role of WB 18 FDG PET/CT in patients (pts) affected with malignant pleural mesothelioma (MPM), who were scheduled for multimodal therapy (MMT): chemotherapy (ChT), radio therapy and surgery.

Methods 28 Pts (18 men, 10 women; age ranging 43-75 years), supstected for MPM at CT, underwent WB 18 FDG PET/CT (Siemens Biograph 16sl, 3D) before (pre-ChT) and post-ChT. PET/CT analisys was visual and semi-quantitative for obtaining tumour uptake, ipsilateral and contralateral nodal involvement and distant metastasis. Given the volume of MPM, total metabolic activity was evaluated in a volume of interest (VOI) on both the pre and post-therapy controls, considering it to be potentially more sensitive in detecting change than a single pixel value. SUV max value > 3 was considered as abnormal value. All pts underwent video thoracoscopy and tumors were confirmed as epithelial MPM by histopathology obtained via 5-6 random pleural biopsies.

Results At pre-ChT control, all pts showed abnormal pleural metabolic activity (true positive pts=100%). In comparison with the previous, post-ChT metabolic response defined: -6/28 responder pts, suggesting the continuation of MMT; -Stable Disease in 10/28 pts and Progressive Disease in the last 12/28 ones, thus excluding surgery in a total of 22/28 pts (78.5%). In these last pts PET/CT induced a shift of the therapeutic strategy vs a second line of ChT. At CT alone comparison, WB 18FDG-PET/CT better detected controlateral nodal involvement in 8 pts and distant metastasis which were missed on CT in other 3 ones. In addition PET/CT was more effective than CT in monitoring pts in the FU controls, clearly showing therapeuthic response or disease progression.

Conclusions The 18F-FDG PET/CT can be considered an effective imaging technique for predicting prognosis and monitoring therapeutic response. It can change pts management and can lead or exclude surgery in multimodal therapeutic strategy.