Evaluation of post radiotherapy PSA as a prognostic and predictive biomarker in high risk prostate cancer: A secondary analysis of RTOG 0521.

• DOI: 10.1200/jco.2025.43.5_suppl.384
• Publication Date: 2025-02-18T14:35:11Z
• Authors: Paul Koffer; Christina Raker; Thomas A. DiPetrillo; Benedito A. Carneiro; Anthony E. Mega; Howard M. Sandler; George B Rodrigues; Amit B Shah; Jason A. Efstathiou; Susan Chafe; Alexander G. Balogh; Scott G Williams; Deborah A. Kuban; Elizabeth Gore; Jessica Karen Wong; Marie Duclos; Paul L. Nguyen; Felix Y Feng

384 Background: RTOG 0521 was a randomized trial of radiotherapy (RT) and 24 months androgen deprivation (ADT) with without docetaxel (D) in high risk prostate cancer. We sought to evaluate whether post RT PSA prognostic outcomes predictive the benefit D. hypothesized that patients higher derive from D while those lower would no benefit. Methods: Patients treated on received 72-75.6 Gy 40-42 fractions 8 weeks after starting ADT. In experimental arm, started 28 days RT. Per protocol, be drawn within completion (PRT-PSA). Hazard ratios (HRs) for PRT-PSA (>/≤ median level) were estimated by Cox proportional hazards regression overall survival (OS) Fine-Gray competing risks specific mortality (PCSM) distant metastasis (DM), adjusting baseline characteristics. As sensitivity analysis non-proportional hazards, HRs follow up censored at 10 years. Results: available 276/563 (114/281 ADT alone 162/282 ADT+D arm). 15 120 randomization. 25% had >0.1 ng/L. ng/mL worse OS (HR 2.39, 95% confidence interval [CI] 1.51-3.79), PCSM 3.78, CI 1.87-7.62), DM 3.54, 1.99-6.31) (all p<0.001). Baseline characteristics including Gleason score, T-stage, pretreatment PSA, performance status, age similar between ≤ 0.1 ng/mL. ng/mL, there seen addition terms 1.06, p=0.88), 0.97, p=0.96), or 1.16, p=0.75). ≤0.1 0.55, p=0.03) 0.36, p=0.02) but significant 0.74, p=0.40). Results (OS HR 1.36, p=0.42; 1.71, p=0.39) 0.41, p=0.003; 0.26, p=0.006). Conclusions: OS, DMFS, cancer long term +/- Despite having prognosis, did not an Clinical information: NCT00288080 . (ng/mL) ADT, event/total ADT+D, Adjusted (95% CI) CI)-10 y 28/79 31/127 0.55 (0.32-0.95) 0.41 (0.23-0.73) 21/35 18/35 1.06 (0.51-2.19) 1.36 (0.64-2.88) 13/79 7/127 0.36 (0.15-0.87) 0.26 (0.10-0.67) 15/35 11/35 0.97 (0.29-3.21) 1.71 (0.51-5.70) 14/79 16/127 0.74 (0.37-1.50) 0.75 16/35 1.16 (0.47-2.85) 1.09 (0.43-2.75)