PD63-04: Detectable Prostate-specific antigen value between 0.01 - 0.1ng/ml following robotic-assisted radical prostatectomy (RARP): Does it correlate with future biochemical recurrence?

Ahmed Sayed Zakaria, Amr Hodhod, Hanna Shahine, Félix Couture, Côme Tholomier, David-Dan Nguyen, Cristina Negrean, Kyle Law, Pierre Karakiewicz Karakiewicz, Assaad El-Hakim, Kevin Zorn

Introduction: Ultrasensitive PSA assays is widely used in the early detection of biochemical recurrence (BCR) after RARP, setting a value of <0.01ng/ml rather than the regular value of <0.1ng/ml. Yet, the impact on future BCR of having a nadir and persistently detectable follow-up PSA between 0.01-0.1ng/ml, is still unclear. Our aim was to characterize PSA changes over time in this setting and to assess for further progression.

Methods: We conducted a retrospective review of 1359 men who underwent RARP in two high-volume centers, between 2006 and 2019. Patients were followed with PSA at 1,3,6,9,12,18,24,30 and 36 months then annually after. We included patients with PSA nadir value between 0.01-0.1ng/ml within 6 months of surgery and with at least 2 follow-up measurements within the same range. Within our cohort, we divided patients based on their BCR status and analyzed oncological outcomes and PSA evolution. Multi-variable Cox (MVC) hazard models were used to analyze variables predicting BCR-free survival (BCR-FS).

Results: 167 (12.3%) subjects were identified for analyses, with a mean follow-up time of 60.2 ±31.4 months (Table 1). In our cohort, 5-year BCR-FS rate was 86%, 32 (19.1%) patients had BCR, with a mean time to BCR of 43.7±24.3 months. Subsequently, 26 (15.5%) patients received salvage radiotherapy. During follow-up, BCR-free patients had stable mean PSA values = 0.03 ng/ml while patients who developed BCR showed a slowly rising trend over time with a significant difference between groups starting at 9 months (P<0.023), even when values = 0.10 ng/ml were excluded (Fig.1). In the MVC model, rising PSA (continuous) starting at 9 months was a significant predictor of BCR [(HR:2.7; 95%CI: 1.6-3.82) P=0.013].

Conclusions: Our study demonstrated that a considerable number of men have detectable PSA values ranging between 0.01-0.1ng/ml post-RARP. They can still be followed regularly to avoid patients’ anxiety and unnecessary radiotherapy. Close follow-up is still required. Source of

Funding: None