BACKGROUND: Selecting appropriate candidates for postprostatectomy radiotherapy is challenging, because adverse pathological features cannot accurately predict clinical recurrence. Biomarkers that identify residual disease activity may assist clinicians when counseling patients on the risks, benefits and costs of secondary treatment. NADiA ProsVue PSA slope results ≤2.0 pg ml(-1) month(-1) are predictive of a reduced risk of clinical recurrence; however, its clinical utility has not yet been studied. METHODS: We prospectively enrolled men treated by radical prostatectomy in a multicenter, institutional review board-approved clinical trial. At postsurgical follow-up, investigators (N=17) stratified men into low-, intermediate- or high-risk groups for prostate cancer recurrence based on clinicopathological findings and other factors. Investigators documented their initial treatment plan for each subject and serially collected three serum samples for ProsVue testing. After the ProsVue result was reported, investigators recorded whether or not the initial treatment plan was changed. The proportion of cases referred for secondary treatment before and after ProsVue was reported, and the significance of the difference determined. RESULTS: Complete assessments were reported for 225 men, 128 (56.9%) of whom were stratified into intermediate- and high-risk groups. Investigators reported that they would have referred 41/128 (32.0%) at-risk men for secondary treatment. However, after results were known, they referred only 15/128 (11.7%) men. The difference in proportions (-20.3%, 95% confidence interval (CI) -29.9 to -10.3%) is significant (P<0.0001). Odds of a referral was significantly reduced after results were reported (odds ratio 0.28, 95% CI 0.15-0.54, P<0.0001). CONCLUSIONS: Knowledge of a ProsVue result had significant impact on the final treatment plan. A ProsVue result ⩽2.0 pg ml(-1) month(-1) significantly reduced the proportion of men at risk of recurrence who otherwise would have been referred for secondary treatment.