Prognostic value of baseline imaging parameters prior to therapy with177Lu-PSMA-617

84 Aim: The aim of this study was to investigate the prognostic value of imaging parameters on FDG-PET, PSMA-PET and bone scintigraphy for progression-free survival (PFS) and overall survival (OS) in patients undergoing Lutetium-177-PSMA617 (LuPSMA) therapy. Methods: Between 10/2015 and 12/2016, 30 patients who received up to 4 cycles of LuPSMA in a prospective study were included. All patients underwent FDG PET/CT, PSMA PET/CT, and bone scintigraphy before the first cycle. PFS and OS of patients were recorded from the first cycle to the time of this analysis. The parameters SUVmax, SUVmean and volume from FDG PET and PSMA PET were measured. For FDG PET, all disease with SUV greater than liver + 2 standard deviations was encompassed (MIM Software). For PSMA-PET, a SUV threshold of 3 was used. For bone scintigraphy, BSI and Number of Lesions were measured (EXINI Bone Scan Index). Survival time analyses used Kaplan-Meier procedures, log-rank test and Cox regression models. Results: In the univariate Cox regression, only the tumor volume in FDG-PET was significant for PFS (p = 0.026) and OS (p = 0.016). Other parameters were not significant. Patients with FDG-positive tumor volume above 500 ml had a shorter overall survival (Median 194 vs. 505 days; p = 0.0052). Conclusions: The results of this work suggest that the FDG-positive tumor volume can be used as a prognostic marker for patients receiving LuPSMA therapy. Together with known prognostic parameters such as ALP, imaging parameters could help identify high-risk patients.