Kinetic analysis of focal hypoechoic lesion in the prostate treated by castration

Dynamic changes in the focal hypoehoic lesion (FHL) in the prostate, visualized by transrectal sonography (TRS), were determined in five patients with prostatic cancer (PC) after treatment by castration. In all cases, the volume of FHL, as well as the volume of the whole prostate, decreased exponentially after castration. In four out of five cases, the volume (not including the FHL, which might suggest the volume of the normal tissues) increased slightly in the early postoperative weeks, and decreased thereafter. In the remaining one case, it decreased consecutively. According to the formula established in our previous study, the reduction time (tau) of the volume of the whole prostate and of the volume of the FHL was calculated, indicating that the tau of the FHL was remarkably shorter than that of the volume not indicating the FHL. This evidence suggested that not only the cancerous tissues but also the normal prostatic tissues might reduce in volume after castration.