Ten-year disease progression and mortality rates in men who experience biochemical recurrence versus persistence after radical prostatectomy and undergo salvage radiation therapy: A post-hoc analysis of RTOG 9601 trial data.

PURPOSE

To compare local/metastatic disease progression and overall mortality rates in men with node-negative prostate cancer at radical prostatectomy (RP) that experience biochemical recurrence vs. persistence postoperatively and undergo salvage radiation therapy (sRT).

MATERIALS AND METHODS

Data on 760 men who participated in the RTOG 9601 trial were extracted using the NCTN data archive platform. Patients were stratified into biochemical recurrence (nadir-PSA ≤0.4 ng/ml) or persistence (nadir-PSA >0.4 ng/ml) groups, based on the cut-off reported in the original trial. Inverse probability of treatment weighting (IPTW) methodology was utilized to minimize the baseline differences among groups. Competing-risk and Kaplan-Meier analyses estimated the impact of prostate-specific antigen (PSA) persistence vs. recurrence on local and metastatic disease progression and overall-mortality in the IPTW-adjusted model; a 2-sided P < 0.05 was considered significant.

RESULTS

All patients received sRT, and about 50% of the patients in either group received concomitant antiandrogen therapy (P = 0.951). The median follow-up was 12 years. After IPTW, the 2 groups were well-matched with standardized mean differences ∼10%. In the IPTW-adjusted cohort, the 10-year local and metastatic disease occurrence rates were 3.2% vs. 1.4% (Gray's P = 0.0001) and 28.6% vs. 10.1% (Gray's P < 0.0001) in patients with persistent vs. recurrent PSA, respectively. Similarly, the 10-year overall-mortality rates were 24.9% vs. 11.9% (Log-rank P = 0.029), respectively.

CONCLUSIONS

Patients with biochemical persistence after RP are approximately 2.5 times more likely to experience local/metastatic failure and death, compared to patients with biochemical recurrence after RP, despite equivalent sRT with/without antiandrogen therapy use. These data may facilitate patient counseling and shared treatment selection.