Prostate-specific antigen decline pattern in advanced prostate cancer receiving androgen deprivation therapy and relationship with prostate-specific antigen progression

Prostate-Specific Antigen Kinetics Effects on Outcomes of Low-Volume Metastatic Prostate Cancer Patients Receiving Androgen Deprivation Therapy

Background

The present study aimed to analyse factors influencing the effects of androgen deprivation therapy (ADT) in patients with newly diagnosed metastatic castration-naïve prostate cancer (mCNPC), especially in low-volume disease (LVD), according to subclassification of metastatic prostate cancer established by the CHAARTED trial.

Materials and 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

48.3% of LVD patients progressed to castration-resistant prostate cancer (mCRPC). Among them, CRPC group had significantly shorter time to PSA nadir (TTN) and faster time from PSA nadir to CRPC (TFNTC) (p < 0.001) compared to non-CRPC group. PSA doubling time (PSADT) < 4 months tended to be associated with faster disease progression and shorter overall survival (OS). Among all patients with metastatic prostate cancer, those with shorter TTN <9 months, higher nadir PSA level ≥1 ng/mL, and shorter PSADT <3 months had increased tendency for biochemical progression.

Conclusions

PSADT is an effective clinical predictor for disease progression and survival in LVD. Other PSA kinetics including TTN and TFNTC, though not the major predictors for disease progression or OS in LVD, might be the predictors for disease control status.

The Importance of Time to Prostate-Specific Antigen (PSA) Nadir after Primary Androgen Deprivation Therapy in Hormone-Naïve Prostate Cancer Patients

Prostate-specific antigen (PSA) is currently the most useful biomarker for detection of prostate cancer (PCa). The ability to measure serum PSA levels has affected all aspects of PCa management over the past two decades. The standard initial systemic therapy for advanced PCa is androgen-deprivation therapy (ADT). Although PCa patients with metastatic disease initially respond well to ADT, they often progress to castration-resistant prostate cancer (CRPC), which has a high mortality rate. We have demonstrated that time to PSA nadir (TTN) after primary ADT is an important early predictor of overall survival and progression-free survival for advanced PCa patients. In in vivo experiments, we demonstrated that the presence of fibroblasts in the PCa tumor microenvironment can prolong the period for serum PSA decline after ADT, and enhance the efficacy of ADT. Clarification of the mechanisms that affect TTN after ADT could be useful to guide selection of optimal PCa treatment strategies. In this review, we discuss recent in vitro and in vivo findings concerning the involvement of stromal–epithelial interactions in the biological mechanism of TTN after ADT to support the novel concept of “tumor regulating fibroblasts”.