Tumor volume and prostate-specific antigen kinetics effects on outcomes of metastatic prostate cancer patients receiving androgen deprivation therapy

Background The present study aimed to analyse the effects of androgen deprivation therapy (ADT) in patients with newly diagnosed metastatic castration-naïve prostate cancer (mCNPC) and explore predictors, particularly prostate-specific antigen (PSA) kinetics, associated with poor prognosis according to tumor volume, a new sub-classification of metastatic prostate cancer established by the CHAARTED trial.Methods We reviewed 648 patients with newly diagnosed mCNPC receiving ADT at Chang Gung Memorial Hospital from January 2007 to December 2016. Basic characteristics and PSA kinetics profile were subsequently evaluated.Results Among patients with high-volume disease, those with faster time to PSA nadir (TTN) (< 7 months), higher PSA nadir (≥ 2 ng/mL), and faster PSA doubling time (PSADT) (< 2 months) had higher risk for faster disease progression or shorter overall survival (OS) compared to those with slower TTN (> 7 months), lower PSA nadir (< 2 ng/mL), and slower PSADT (> 2 months). Multivariate analysis of those with low-volume disease showed that only PSADT (< 4 months) was tended to be associated with faster disease progression or shorter OS.Conclusions PSA kinetics are effective clinical predictors for risk of disease progression and survival. Moreover, various PSA kinetics should be monitored according to tumor volume.