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) ( 7 months), lower PSA nadir ( 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.