Nonpalpable cancer of the prostate: assessment with transrectal US

Palpable cancer of the prostate is widely believed to be clinically significant. The authors compared the clinical significance of palpable prostate cancer with nonpalpable prostate cancer discovered with transrectal ultrasound (US). A strong association between lesion volume measured with preoperative transrectal US and volumetric measurements in 60 radical prostatectomy specimens permitted the use of tumor size measured with transrectal US as a reasonable estimation of gross tumor volume. In a subsequent clinical series, 147 biopsy-proved cancers were grouped according to size measured at US, the findings at digital rectal examination (DRE), and the Gleason score. For the 147 patients with known prostate cancer, a statistically significant difference between Gleason scores of palpable and nonpalpable cancers could not be demonstrated when the size of the tumor and its location within the prostate were held constant. Assuming that the Gleason score is a reliable indication of malignant potential and clinical significance, the authors conclude that nonpalpable prostatic cancer detected with transrectal US alone may be just as clinically significant as prostatic cancer discovered with DRE.