As salvage radiotherapy (SRT) outcomes may be affected by factors associated with prostatectomy findings, they may be positively affected when used at lower prostate-specific antigen (PSA) levels, according to a study published in the Journal of Clinical Oncology.1
Researchers led by Bradley Stish, MD, of the Mayo Clinic, Rochester Minnesota, reviewed 1106 patients who received SRT between January 1987 and July 2013 to determine outcomes of SRT for men with detectable PSA after radical prostatectomy. The researchers measured for outcomes of overall survival and cumulative incidence for biochemical recurrence (BcR), distant metastases (DM), and cause-specific mortality (CSM) through Kaplan-Meier.
On multiple variable analysis, pathologic tumor stage, Gleason score, and pre-SRT PSA were found to be associated with BcR, DM, CSM, and OS. Androgen suppression and SRT doses that were greater than 68 Gy were found to be associated with BcR, and age was associated with OS.
In addition, each pre-SRT PSA doubling was found to have increased significantly the relative risk of BcR, DM, CSM, and all-cause mortality.
Using a pre-SRT PSA cutoff of 0.5 ng/mL or greater vs more than 0.5 ng/mL, they found that 5-year and 10-year cumulative incidences were the following, respectively: 42% vs 56% and 60% vs 68% for BcR; 7% vs 14% and 13% vs 25% for DM; 1% vs 4% and 6% vs 13% for CSM; and 94% vs 92% and 83% vs 73% for OS.
“These findings argue against prolonged monitoring of detectable postprostactectomy PSA levels that delay initiation of SRT,” the authors concluded.
1. Stish BJ, Pisansky TM, Harmsen WS, et al. Improved metastasis-free and survival outcomes with early salvage radiotherapy in men with detectable prostate-specific antigen after prostatectomy for prostate cancer. J Clin Oncol. 2016 Aug 1. doi: 10.1200/JCO.2016.68.3425. [Epub ahead of print.]