Transrectal ultrasound: impact on clinical staging

New data just published by a group at the University of California, San Francisco (UCSF) suggests that, in the current era, transrectal ultrasound (TRUS) provides an accurate means to assess the clinical (pre-treatment) stage of a man’s prostate cancer.

Most clinicians rely on a digital rectal examination (DRE) to assess clinical stage of prostate cancer at the time of diagnosis because of conflicting data from earlier studies in the literature regarding the role of transrectal ultrasonography (TRUS). However, ultrasound technologies and physician experience have improved since most of those early data were published, and so Eisenberg et al. set out to assess the impact of TRUS on the clinical staging of prostate cancer in a contemporary patient cohort.

In 2002, a standardized form was introduced at UCSF for reporting TRUS findings prostate cancer patients. The primary goal was to be able to rank the clinical suspicion of extracapsular extension (ECE). Preoperative clinical findings were compared with pathological staging as assessed by analysis of radical prostatectomy specimens for 620 patients treated between 2002 to 2007. The results reported by Eisenberg et al. are as follows:

  • Mean patient age was 58 ± 6.6 years with a mean PSA of 7.0 ± 4.5 ng/ml.
  • 157/620 patients (25.3 percent) had pathologic ECE.
  • Evidence of ECE by TRUS was very highly associated with higher pathologic stage and higher rates of biochemical failure after prostatectomy.
  • Overall, TRUS had a 31 percent sensitivity, 92 percent specificity, 58 percent positive predictive value, and 80 percent negative predictive value  for the detection of ECE.
  • TRUS alone was significantly more accurate in predicting ECE than commonly used nomograms or tables when examining patients with impalpable tumors.

This paper raises the question of whether TRUS findings should be incorporated into the Partin tables and the Kattan nomograms to improve the accuracy of these widely used prognostic tools in order to improve their accuracy and thereby assist in the selection of appropriate treatments for individual patients. Such improved accuracy may be of particular importance in the use of radiation and other forms of non-surgical treatment, where one does not have the benefit of being able to re-stage the cancer post-surgery by assigning a pathological stage.

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