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

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.