Newswise — High-intensity focused ultrasound (HIFU) represents a minimally invasive approach to treating prostate cancer (CaP). It is presently not FDA approved in the US, but experience with the approach exists in Europe. In the January 2009 edition of the Journal of Urology, Dr. Luigi Mearini and associates report on their experience with the Sonoblate 500 in the treatment of 163 CaP patients.
HIFU induces coagulative necrosis of prostate tissue by thermal effects and cavitation. It is delivered by transrectal ultrasound guided probes. This is a prospective study of 163 men with clinical stages T1-T3N0M0 CaP. A prostatic calcification of >1cm, anal stricture, or prostate volume >50cc were exclusion criteria. This report differs from others, in that none of the patients underwent TURP or neoadjuvant androgen deprivation therapy prior to HIFU. Treatment was under spinal or general anesthesia in a day surgery suite, but patients were kept overnight then discharged on 3 weeks of antibiotics and anti-inflammatory agents. Urinary symptoms were evaluated by the IPSS questionnaire and sexual function by the IIEF-5 questionnaire. Eight-core prostate biopsy was performed at 6 months. Biochemical failure was defined by the Phoenix criteria of nadir PSA plus 2ng/ml.
A total of 28 of the 163 patients had a second HIFU treatment, most commonly due to prostate size or residual tumor. Intra- and post-operative complications were reported as rectal fistula in 1 patient 2 months after HIFU. The median patient age was 72 years, median PSA was 7.3ng/ml, and stage was T1 in 44.1%, T2 in 42.5% and T3 in 13.4%. Gleason biopsy score was 5-7 in 76.7%. D'Amico classification stratified patients as low risk in 80 men, intermediate risk in 47, and high risk in 14. The report classified 22 men with stage T3a disease as very high risk. Pretreatment parameters included median prostate volume equal to 32.4cc, median maximum urinary flow rate as 12cc/sec, median IPSS 10 and median IIEF-5 as 16. The Foley catheter or supra-pubic tube was removed at a median of 13 days. Median follow-up was 23.8 months and 3 men were lost to follow-up.
Median PSA nadir was 0.15ng/ml, reached at a median time of 2.3 months. In men undergoing a single treatment, the 6-month positive biopsy rate was 33.9% and regression analysis showed that a PSA nadir >0,4ng/ml had an independent predictive value for local failure. Negative biopsy rates for low, intermediate, high and very high-risk patients were 75.6%, 77.4%, 35.7%, and 18.7%. Biochemical disease free status was found in 125/160 men (78.1). Independent predictive value for biochemical relapse included PSA nadir >0.4ng/ml and risk stratification. Three-year biochemical-free survival rates for low, intermediate, high and very high-risk patients were 86.1%, 79.6%, 56.4%, and 19.6%. Maximum urinary flow rates at 6 months improved 25% from baseline to 16cc/sec and IPSS decreased 30% to a median of 7. Urinary incontinence was uncommon, but 15% developed urethral stricture.
Importantly, this study did not use pre-HIFU TURP or androgen deprivation therapy. However, a 25% 6-month positive biopsy rate in low risk patients would have to be carefully compared to standard options as HIFU goes forward.
Mearini L, D'Urso L, Collura D, Zucchi A, Costantini E, Formiconi A, Bini V, Muto G, Porena M
Written by Christopher P. Evans, MD, FACS