How reliable is the high-volume definition in prostate cancer patients: the potential game-changing role of PSMA

PurposeTo evaluate whether metabolic and volumetric data from Ga-68-PSMA PET/CT performed during staging of de-novo high-volume mCSPC patients who received docetaxel could be used to predict survival. MethodsForty-two de-novo high-volume mCSPC patients, who received ADT + Docetaxel and underwent Ga-68-PSMA PET/CT for staging, were included in the study. The association between patients' pathological data, all PSA measurements, treatments they received, the data obtained from Ga-68-PSMA PET/CT and progression-free and overall survival were examined. ResultsIn the multivariate analysis, PSMA-TV (primary) and PSMA-TV (WB) variables were shown to be independent negative predictors of overall survival. For the threshold value of 19.91 cm(3) obtained for PSMA-TV (primary), HR was calculated as 6.31, the 95% confidence interval (CI): 1.01-39.18, P = 0.048. For the threshold value of 1226.5 cm(3) obtained for PSMA-TV (WB) variable, HR was calculated as 58.62, the 95% CI: 2.55-1344.43, P = 0.011. In our study, SUVmax (WB) variable was found to be an independent and negative predictor of progression-free survival. For the determined threshold value of 17.74, HR was calculated as 16.24, 95% CI: 1.18-22.76, P = 0.037. ConclusionMetabolic and volumetric data obtained from Ga-68-PSMA PET/CT can be used to predict survival in de-novo high-volume mCSPC. Our results show that in ADT + Docetaxel receiving patients, a subgroup with higher PSMA-TV (WB) values have a significantly worse prognosis. This situation suggests that the high-volume disease definition in the literature may be insufficient for this group, and that Ga-68-PSMA PET/CT can play an essential role in demonstrating the heterogeneity within the group.