Local control of prostate cancer by transrectal high intensity focused ultrasound therapy: Preliminary results

Purpose: We conducted a phase I/II study to evaluate the efficacy of transr ectal high intensity focused ultrasound in the treatment of localized prost ate cancer and to assess associated complications. The efficacy of a new hi gh intensity ultrasound device was evaluated using posttreatment prostate s pecific antigen (PSA) levels and histological results from prostate biopsie s as end points. Materials and Methods: A total of 113 transrectal high intensity focused ul trasound sessions were performed in 50 patients with localized prostate can cer, who were not suitable candidates for radical prostatectomy. Of these p atients 2 underwent salvage ultrasound treatment for locally recurrent canc er following definitive radiation therapy. Mean plus or minus standard devi ation patient age, PSA and prostate volume were 70.7 +/- 4.54 years, 9.61 /- 1.42 ng./ml. and 37.3 +/- 19.1 cc. The 2 different high intensity ultras ound prototypes were successfully used, and the latter prototype included s everal safety devices to reduce morbidity. Median followup was 24 months (r ange 3 to 46). Control parameters were changes in PSA and random control se xtant biopsies at 1 to 3, 3 to 12, 12 to 24, 24 to 36 and 36 to 48 months. Results: For the evaluation of therapy patients were divided into 4 groups. Group 1 (complete response) included 28 patients (56%) with no residual ca ncer and PSA less than 4 ng./ml. (mean 0.93), group 2 (biochemical failure) 3 patients (56%) with no residual cancer and PSA greater than 4 ng./ml. (m ean 6.22), group 3 (biochemical control) 9 patients (18%) with residual can cer (mean positive biopsy 1.1 of 6) and PSA less than 4 ng./ml. (mean 0.90) , and group 4 (failures) 10 patients (20%) with residual cancer (mean posit ive biopsies 1.9 of 6) and BSA greater than 4 ng/ml. (mean 8.9). Of the 10 cases in group 4 hormone therapy was required in 3 and radiotherapy in 5. C omplication rate with the first prototype device was 50% and it decreased t o 17% with the second prototype. Conclusions: Morbidity associated with high intensity focused ultrasound tr eatment is currently minimal. Local control of the localized prostate cance r was observed in groups 1, 2 and 3 (80%). Repeat sessions were deferred in groups 2 and 3 based on changes in PSA. These preliminary data suggest tha t high intensity focused ultrasound represents a valid alternative treatmen t strategy for patients with localized prostate cancer who are unsuitable f or surgery.