Increasing prostate-specific antigen (PSA) levels prior to salvage radiotherapy were significantly associated with an increased risk of distant metastasis and cause-specific mortality but not overall survival among men with detectable PSA following radical prostatectomy, according to a report published in the Journal of Clinical Oncology.
Investigators retrospectively studied 1,106 consecutive patients with surgically staged prostate cancer who received salvage radiotherapy (SRT) and who had a documented PSA of 0.1 ng/mL or greater. A total of 208 patients developed distant metastasis during median follow-up of 8.9 years.
In multivariate analysis, each doubling of pre-SRT PSA was associated with a 32% increased risk of distant metastasis (P less than .001), reported Bradley J. Stish, MD, and his associates at the Mayo Clinic (J Clin Oncol. 2016 Aug. doi: 10.1200/JCO.2016.68.3425).
Each pre-SRT PSA doubling also significantly increased the relative risk of cause-specific mortality (HR, 1.40; P less than .001) but not overall survival (HR, 1.12; P = .02).
More advanced tumor stages, higher Gleason scores, and higher PSA levels prior to salvage radiotherapy were significantly associated with an increased risk of biochemical recurrence. Salvage radiotherapy dose greater than 68 Gy and use of androgen suppression were associated with reduced risk of biochemical recurrence. Overall survival was 92.9% (95% confidence interval, 91.3%-94.5%) at 5 years and 77.3% (95% CI, 74.2%-80.5%) at 10 years. The cause-specific mortality rates were 3.0% (95% CI, 1.9%-4.0%) at 5 years and 10.4% (95% CI, 8.0%-12.6%) at 10 years.
“When taken together, these findings provide strong evidence supporting the clinical benefits attributable to early [salvage radiotherapy] in men with detectable PSA after [radical prostatectomy],” investigators wrote.
Beginning salvage radiotherapy treatment at the lowest PSA level is “most beneficial for long-term therapeutic efficacy,” they added.
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