Prostate-specific antigen after neoadjuvant androgen suppression in prostate cancer patients receiving short-term androgen suppression and external beam radiotherapy: pooled analysis of four NRG Oncology RTOG randomized clinical trials.

To validate if prostate specific antigen (PSA) level after neoadjuvant androgen suppression (neoAS) is associated with long-term outcome after neoAS and external radiation therapy (RT) with concurrent short-term AS in prostate cancer patients.

2404 patients treated with neoAS prior to RT and concurrent AS (without post-RT AS) were pooled from trials A, B, C, and D. Multivariable models were used to test associations between the pre-specified dichotomized post-neoAS, pre-RT PSA (≤0.1 vs. >0.1 ng/mL) groupings and clinical outcomes.

Median follow-up for surviving patients was 9.4 years. Median post-neoAS, pre-RT PSA was 0.3 ng/mL, with 32% of patients ≤0.1 ng/mL. Race, Gleason score, T-stage, N-stage, pre-treatment PSA, and duration of neoAS were associated with the groups of patients with PSA ≤0.1 and >0.1 ng/mL. In univariate analyses, post-neoAS, pre-RT PSA >0.1 ng/mL was associated with increased risks of biochemical failure (hazard ratio [HR] 2.04; p<0.0001), local failure (HR 2.51; p<0.0001), distant metastases (HR 1.73; p=0.0006), cause-specific mortality (HR 2.36; p<0.0001), and all-cause mortality (HR 1.24; p=0.005). In multivariable models that also included baseline and treatment variables, post-neoAS, pre-RT PSA >0.1 ng/mL was independently associated with increased risk of biochemical failure (HR 2.00; p<0.0001), local failure (HR 2.33; p<0.0001), and cause-specific mortality (HR 1.75; p=0.03).

Patients with PSA >0.1 ng/mL after neoAS and before RT start had less favorable clinical outcomes than patients with PSA was ≤0.1 ng/mL. The role of post-neoAS, pre-RT PSA presently, relative to PSA obtained along the continuum of medical care, is not presently defined, but could be tested in future clinical trials.

International journal of radiation oncology, biology, physics. 2019 Apr 05 [Epub ahead of print]

Christopher L Hallemeier, Peixin Zhang, Thomas M Pisansky, Gerald E Hanks, David G McGowan, Mack Roach, Kenneth L Zeitzer, Selim Y Firat, Siraj M Husain, David P D'Souza, Luis Souhami, Matthew B Parliament, Seth A Rosenthal, Himanshu R Lukka, Marvin Rotman, Eric M Horwitz, Edward F Miles, Rebecca Paulus, Howard M Sandler

Mayo Clinic, Rochester, MN. Electronic address: ., NRG Oncology Statistics and Data Management Center, Philadelphia, PA., Mayo Clinic, Rochester, MN., Fox Chase Cancer Center, Philadelphia, PA., Cross Cancer Institute, Edmonton, AB, Canada., University of California, San Francisco, San Francisco, CA., Thomas Jefferson University Hospital, Philadelphia, PA., Medical College of Wisconsin-Zablocki VA Medical Center, Milwaukee, WI., Tom Baker Cancer Centre, Calgary, AB, Canada., London Regional Cancer Program, London, ON, Canada., McGill University Health Centre, Montreal, QC, Canada., Radiological Associates of Sacramento, Sacramento, CA., McMaster University, Juravinski Cancer Center, Hamilton Health Sciences, Hamilton, ON, Canada., Brooklyn MB-CCOP/SUNY Downstate, Brooklyn, NY., Naval Medical Center accruals Dartmouth Hitchcock Medical Center, Portsmouth, VA., Cedars-Sinai Medical Center, Los Angeles, CA.