Presentation Authors: Akshay Sood*, Jacob Keeley, Sohrab Arora, Deepansh Dalela, Wooju Jeong, Craig G Rogers, James Peabody, Mani Menon, Firas Abdollah, Detroit, MI
Introduction: To evaluate rates and patterns of local and metastatic disease occurrence in patients with node-negative non-metastatic prostate cancer at radical prostatectomy (RP) that experience PSA elevation (recurrence or persistence) and undergo salvage radiation therapy (sRT).
Methods: All available demographic, tumor-specific, treatment-specific, and local and metastatic disease occurrence data from 760 men who participated in the RTOG 9601 trial were extracted using the Project Data Sphere platform. Patients were stratified into PSA recurrence (post-RP PSA nadir < 0.5 ng/ml) or PSA persistence (post-RP PSA nadir =>0.5 ng/ml) groups, based on cutoffs reported in the original trial. Inverse probability of treatment weighting (IPTW) analysis was utilized to minimize the baseline differences among the groups. Competing risk analysis tested the impact of PSA persistence versus recurrence on local and metastatic disease in IPTW-adjusted model.
Results: Patients that experienced PSA persistence had higher Gleason grade disease (p=0.027), more advanced pathological stage (p=0.024), and higher PSA levels at the time of receipt of salvage therapy (p < 0.001; Table 1). All patients received sRT, and approximately 50% of the patients in each group received concomitant anti-androgen therapy (p=0.951; Table 1). The median follow-up was 12 yrs. In the IPTW-adjusted cohort, the 10-yr local recurrence rates were 3.2% versus 1.4% in patients with persistent versus recurrent PSA (Gray test p=0.0001; Figure 1b). Similarly, 10-yr metastatic recurrence rates were 28.6% versus 10.1% in patients with persistent versus recurrent PSA (Gray test p < 0.0001; Figure 1a).
Conclusions: Patients with PSA persistence after RP are approximately 2.5 times more likely to experience local and metastatic disease, when compared to patients with PSA recurrence after RP, despite local sRT with/without anti-androgen therapy. These data may facilitate patient counseling and shared treatment selection.