MP57-19: Validation of Prostate Specific Antigen Doubling Time kinetics following Radical Prostatectomy to Guide Active Observation and Intervention

Erica Huang*, Linda My Huynh, Adam Gordon, Ryan Chandhoke, Orange, CA, Blanca Morales, San Francisco, CA, Douglas Skarecky, Joshua Tran, Thomas Ahlering, Orange, CA

Introduction: Biochemical recurrence (BCR) following radical prostatectomy (RP) has limited ability to predict metastatic progression or prostate cancer specific mortality (PCSM). In our experience, a significant number of men with BCR have non-lethal BCR that can be safely observed based on PSA doubling time (DT) and subsequent DT change without radiation (RT) and/or androgen deprivation therapy (ADT). The present study seeks to validate the use of DT kinetics to direct active observation (AO) and intervention.

Methods: A retrospective cohort analysis of 1864 men who underwent RP between June 2002 and September 2019 was conducted. Patients were assessed for treatment intervention (RT and/or ADT) versus AO with DT kinetics. Our main outcome was the predictive value of multivariate regression models for no treatment via ROC analysis. Secondary outcomes were PCSM via Kaplan-Meier analysis.

Results: 407/1864 (21.8%) men experienced BCR (PSA > 0.2 ng/dl, x2), with median follow-up of 7.6 years (IQR 3.3-11.9) (Table 1). In multivariable analysis, DT>12 months (OR: 8.93, 95%CI: 4.53,17.6) and increasing DT (OR: 5.49, 95%CI: 2.81,10.71) were significant predictors for continued observation without treatment (p < 0.001), while pGGG, p-stage, age, and preoperative PSA were not. This model was an excellent predictor for continued no treatment (AUC=0.83). No patients with DT>12 months, increasing DT experienced PCSM (Figure 1).

Conclusions: In our experience, one third of patients with BCR were observed without RT and/or ADT, with 0% PCSM at mean 7.6 years follow-up. DT>12 months and increasing DT were excellent predictors of no need for treatment. We introduce PSA kinetics as a means for guiding need and/or no need for treatment intervention.

Source of Funding: N/A