Six years' experience with high-intensity focused ultrasonography for prostate cancer: oncological outcomes using the new 'Stuttgart' definition for biochemical failure

Objective: • To determine oncological outcomes after high-intensity focused ultrasonography (HIFU) treatment in patients with localized prostate cancer using a new, more accurate, definition ('Stuttgart' definition) of biochemical failure.

Patients and methods: • We performed a retrospective review of all patients in our centre who received first-line treatment with a second-generation Ablatherm™ device (EDAP-TMS, Lyon, France). • Oncological failure was given either by biochemical failure (prostate-specific antigen, PSA, nadir plus 1.2 g/mL) (Stuttgart definition) or the start of salvage therapy because of a persistently positive biopsy after the HIFU procedure. • The 5-year biochemical-free survival rate and 5-year disease-free survival rate were calculated.

Results: • In total, 53 patients were included (mean age, 72.5 ± 4.5 years, range 60-79 years; 28 low risk and 25 intermediate risk). None had undergone previous hormonal therapy. Mean ±sd follow-up was 45.4 ± 15.5 months (range 16-71 years). Mean (range) pre-treatment PSA was 8.5 ± 4 (0.29-18) ng/mL. The median (range) PSA nadir value was 1 (0.01-14) ng/mL and occurred after a mean (range) of 5.09 (3-24) months. • Overall, 36 patients (67.9%) experienced oncological failure. • These included 33 cases (62.2%) of biochemical failure. A PSA nadir of ≤0.2, 0.21-1.0 and >1 ng/mL was reached in 20.8%, 30.2% and 49% of patients, respectively, and was associated with biochemical failure in 9.1%, 30.3% and 60.6%, respectively. • The 5-year biochemical-free survival rate and disease-free survival rate were 21.7% and 13.5%, respectively. In multivariate analysis, a PSA nadir of >1 ng/mL was significantly associated with a risk of biochemical and oncological failure (P= 0.002 and P < 0.001). • Oncological failure was not associated with any risk group. • No patient died from prostate cancer.

Conclusions: • In our experience, Ablatherm™ treatment for clinically localized prostate cancer was associated with a high rate of biochemical failure as determined by the 'Stuttgart' definition, and did not achieve effective cancer control. • The PSA nadir value after HIFU treatment was a significant predictor of treatment failure.