FDG PET-derived parameters as prognostic tool in progressive malignant pleural mesothelioma treated patients

PurposeThe value of FDG PET-derived parameters in predicting overall survival (OS), local relapse-free survival (LRFS) and distant relapse-free survival (DRFS) in treated patients with malignant pleural mesothelioma (MPM) was evaluated.MethodsThis retrospective evaluation included 55 MPM patients treated between March 2006 and February 2015 with FDG PET/CT-guided salvage helical tomotherapy (HTT) after previous surgery plus chemotherapy. Univariate Cox regression analysis was performed to assess the impact of the following FDG PET-derived parameters: biological target volume (BTV), mean and maximum standardized uptake values (SUVmean/max), metabolic tumour volume (MTV) and total lesion glycolysis (TLG), measured using different uptake thresholds (40%, 50% and 60%). Logistic regression was then performed to identify the best FDG PET-derived parameters for selecting patients with poorer survival.ResultsThe median OS was 9.1months (range 0.0 - 69.6months) after the end of HTT; 54/55 patients were dead at the last follow-up. BTV and TLG40, TLG50 and TLG60 were the most significant predictors of OS (p<0.005). The median OS was 4.8months in patients with MTV60 >5cm(3) and TLG40 >334.4, compared with 13.8months and 16.1months in patients with smaller values, respectively. The median LRFS and DRFS were 6.2months (range 1.2 - 39.4months) and 6.5months (0.0 - 66.4months), respectively. TLG40, TLG50 and TLG60 were significantly correlated with LRFS (p<0.015). Median DRFS was 6.4months in patients with MTV40 >39.6cm(3) and 6.2months in patients with TLG40 >334.4, compared with 17months and 18.8months in patients with smaller values. BTV, TLG40 and MTV40 were also found to be good predictors in patients with poor OS/LRFS/DRFS (median survival times less than the median values).ConclusionFDG PET-derived parameters effectively discriminated patients with a poor prognosis and may be helpful in the selection of MPM patients for salvage HTT.