Correlation of prostate‐specific antigen nadir and biochemical failure after high‐intensity focused ultrasound of localized prostate cancer based on the Stuttgart failure criteria – analysis from the @‐Registry

Study Type – Prognosis (retrospective cohort) Level of Evidence 2b What’s known on the subject? and What does the study add? The prostate‐specific antigen (PSA) nadir after high‐intensity focused ultrasound (HIFU) therapy for clinically localized prostate cancer has been shown to correlate with treatment failure in single centre studies. Purpose was to determine if the PSA nadir after HIFU can be used as a predictor of the biochemical disease‐free survival in a multicentre study. This multicentre analysis confirms that PSA nadir after HIFU predicts biochemical DFSR in a statistically significant manner. OBJECTIVE • To determine if the prostate‐specific antigen (PSA) nadir after high‐intensity focused ultrasound (HIFU) can be used as a predictor of the biochemical disease‐free survival rate (DFSR). PATIENTS AND METHODS • Patient data were derived from the multicentre‐based @‐Registry, the largest registry to report outcomes in patients with localized prostate cancer after Ablatherm® HIFU. • PSA level was measured at 3‐month intervals. Patients were stratified into four PSA nadir groups: group 1, ≤0.2 ng/mL; group 2, 0.21–0.5 ng/mL; group 3, 0.51–1 ng/mL; and group 4, >1 ng/mL. • Biochemical treatment failure was defined according to the Stuttgart definition (PSA nadir + 1.2 ng/mL) and the Phoenix definition (PSA nadir + 2 ng/mL). • Biopsy was performed at 3–6 months post‐HIFU or if a PSA level was recorded that was considered clinically relevant. RESULTS • The present study included 804 patients. Biochemical treatment success rates at 5 years according to the Stuttgart definition for the four PSA nadir sub‐groups were as follows: 84, 64, 40 and 30% for groups 1–4, respectively. • The equivalent 5‐year biochemical success rates using the Phoenix definition were 94, 74, 66 and 47%, respectively. • Significantly more patients had a negative biopsy in the lowest PSA nadir group than in the other sub‐groups (91.6 vs 73.1%; P < 0.001). • The present study is limited by its retrospective nature and variations in clinical practice across participating centres. CONCLUSION • This multicentre analysis confirms that PSA nadir after HIFU predicts biochemical DFSR in a statistically significant manner.