[979] Comparative Analysis of 12-Core Biopsy Results and Tumor Location in Prostatectomy Specimens

Liset Pelaez, Viacheslav Iremashvili, Merce Jorda, Murugesan Manoharan, Daniel L Rosenberg, Mark S Soloway. University of Miami, Miller School of Medicine, Miami, FL

Background: The 12-core transrectal prostate biopsy scheme has emerged as a standard of care. However, quality of sampling may vary in different areas of the prostate included in this procedure. We have analyzed the diagnostic performance of individual prostate biopsy cores.
Design: The study included 250 men who underwent radical prostatectomy at our institution. All participants had a systematic 12-core transrectal prostate biopsy containing lateral and medial cores from each side of the apical, medial and basal thirds of the prostate. After obtaining a 2 mm apical margin the prostatectomy specimens were step-sectioned at 3 to 5-mm intervals in transverse planes into separate blocks. Outlines of each cancer area were drawn on the slides under the microscope and then copied to paper diagrams for prostate sectioning. Biopsy results were matched with histologic maps of the prostatectomy specimens. Sensitivity, negative predictive value (NPV), and overall accuracy were calculated for each biopsy core location and compared between different groups of cores. In addition, patients in the upper quartile of prostate weight were compared to the rest of the cohort.
Results: While in the prostatectomy specimens cancer was found more frequently in the apex, biopsy cores obtained from this third of the prostate were less likely to be positive than mid and basal samples. As a result sensitivity, NPV, and overall accuracy were significantly lower for apical cores. Average NPV and overall accuracy of basal and mid lateral biopsies were inferior to those of medial biopsies on the same levels. However, sensitivity of these lateral cores was similar to that of the medial cores. It should be noted that during pathological examination cancer was much more frequently found in the lateral areas of mid- and basal prostate compared to the medial ones. Sensitivities of apical and mid cores were significantly lower in patients with larger prostates.
Conclusions: Our study has demonstrated significant variations in the quality of sampling of different areas included into the current 12-core transrectal biopsy scheme. Decreased accuracy in lateral mid and basal cores results from higher frequencies of cancer in corresponding prostate areas, and therefore additional samples should be taken at these locations. In addition, diagnostic accuracy of apical cores may be improved through better targeting of the prostatic apex. This may be particularly important in patients with larger prostates.
Category: Genitourinary (including renal tumors)

Wednesday, March 21, 2012 1:00 PM

Poster Session VI # 172, Wednesday Afternoon

 

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