EFFECT OF HIGH-INTENSITY FOCUSED ULTRASOUND ON HUMAN PROSTATE-CANCER IN-VIVO

Transrectal high-intensity focused ultrasound (HIFU) was recently esta blished as a highly effective means of inducing contact and irradiatio n-free intraprostatic coagulative necrosis. This technique, therefore, appears potentially useful for treating Localized prostate cancer (PC ). To evaluate this issue, a total of 29 human prostates with localize d cancer was subjected to HIFU treatment in vivo before radical retrop ubic prostatectomy. HIFU therapy was performed with the use of HIFU tr ansducers with focal lengths of 3.0 cm (n = 3), 3.5 cm (n = 19), and 4 .0 cm (n = 7), and the site intensity was varied from 1260 to 2000 W/c m(2). The extent of intraprostatic necrosis was determined by planimet rical analysis of whole mount prostatic sections. Transrectal HIFU con sistently induced sharply delineated intraprostatic coagulative necros is within the target area, whereas alterations of periprostatic struct ures were never observed. The cross-sectional area of necrosis increas ed from 1.1 +/- 0.7 cm(2) (SD; n = 3; 3.0-cm focal length; 1428 W/cm(2 )) to 1.2 +/- 0.7 cm(2) (n = 2; 3.5-cm focal length; 1428 W/cm(2)), 1. 8 +/- 0.17 cm(2) (n = 8; 3.5-cm focal length; 1680 W/cm(2)), 2.8 +/- 0 .32 cm(2) (n = 9; 3.5-cm focal length; 2000 W/cm(2)) and 3.8 +/- 0.4 c m(2) (n = 7; 4.0 cm focal length; 1260 W/cm(2)). HIFU beam transmissio n and the therapeutic effect were comparable in benign and malignant p rostatic tissue. Interstitial thermometry (n = 6) revealed maximum int raprostatic temperatures in the focal zone up to 98.6 degrees C. Outsi de the focal zone and on the rectal wall, no significant temperature r ises were noted. Subsequently, HIFU was applied to unilateral histolog ically proven T-2n/T-2b PC (12 = 10) in an attempt to destroy all canc er before radical retropubic prostatectomy. PC was always correctly ta rgeted. In 7 individuals, PC was partially (mean, 53%; range, 38-77%) destroyed; in the remaining 3 cases the entire tumor was ablated. Alth ough these histological data permit no definitive conclusion on the cl inical efficacy of this approach, transrectal HIFU seems to be a an at tractive novel minimally invasive treatment option for localized PC.