PATHOLOGY

Prostate needle biopsies: multiple variables are predictive of final tumor volume in radical prostatectomy specimens
Poulos CK, Daggy JK, Cheng L
Department of Pathology and Laboratory Medicine, Indiana University School of Medicine, Indianapolis, Indiana, USA
Cancer. 2004; 101: 527-32

• Background: Tumor volume is one of the most powerful predictors of patient outcome in prostatic adenocarcinoma. It is uncertain as to which preoperative variables are most predictive of final tumor volume at radical prostatectomy, especially among patients who have had positive biopsies at multiple biopsy sites. The current study attempted to identify the biopsy variables that are most predictive of final tumor volume.
• Methods: The authors examined prostate biopsy specimens from 151 consecutive patients with at least 2 positive biopsy sites. The following data were collected: highest percentage of adenocarcinoma at any biopsy site, percentage of adenocarcinoma at the biopsy site with the highest Gleason score, highest percentage of cores positive for adenocarcinoma at any biopsy site, percentage of positive cores with carcinoma at the site with the highest Gleason score, number of positive sites, tumor bilaterality, and percentage of biopsy sites positive for disease. All patients underwent radical prostatectomy. The prostatectomy specimens were entirely embedded and whole mounted. Tumor volume was measured using the grid method. Logarithmic transformation was applied to tumor volumes for the purposes of the analysis.
• Results: Highest percentage of adenocarcinoma at any biopsy site (P = 0.012), percentage of adenocarcinoma at the biopsy site with the highest Gleason score (P = 0.021), number of positive biopsy sites (P = 0.026), tumor bilaterality (P = 0.008), and percentage of biopsy sites positive for disease (P = 0.0001) all were significant predictors of tumor volume on linear regression analysis. Highest percentage of cores positive for adenocarcinoma (P = 0.081) and percentage of positive cores with carcinoma at the site with the highest Gleason score (P = 0.240) were not significant predictors of tumor volume. Based on the model F statistic, percentage of biopsy sites positive for tumor, tumor bilaterality, and highest percentage of adenocarcinoma at any biopsy site were the variables that were most predictive of tumor volume.
• Conclusions: Highest percentage of adenocarcinoma at any biopsy site, percentage of adenocarcinoma at the biopsy site with the highest Gleason score, number of positive biopsy sites, tumor bilaterality, and percentage of biopsy sites positive for disease all are useful preoperative predictors of tumor volume in radical prostatectomy specimens. Although these preoperative biopsy parameters were significant in linear regression models, none was sufficient as a single predictor of tumor volume.
  
  
• Editorial Comment
  The study by Poulos et al. showed that multiple pathologic findings seen in needle biopsies are predictive of final volume in radical prostatectomy specimens. The authors used the grid method for measuring tumor volume. Some institutions have calculated the tumor volume accurately, using computer-assisted image analysis systems. Because this method is not feasible for the routine clinical practice, other investigators have proposed alternative simpler means. The grid method is one of these alternative simpler means that measures tumor extent.
  A number of studies have documented that the tumor extent, the volume or the percentage of prostatic tissue involved by the tumor within the prostate gland may be important prognostic indicators. However, the subject is controversial. Although most authors agree that tumor extension (percentage of carcinoma or tumor volume) in patients with prostate carcinoma should be reported in radical prostatectomies because of its prognostic importance, in some analyses, tumor size has not been considered to be an independent predictor of tumor recurrence (1,2).

References
1. Esptein JI, Carmichael M, Partin AW, Walsh PC: Is tumor volume an independent predictor of progression following radical prostatectomy? A multivariate analysis of 185 clinical stage B adenocarcinoma of the prostate with 5 years of follow-up. J Urol. 1993; 149: 1478-85.
2. Billis A, Magna LA, Ferreira U: Correlation between tumor extent in radical prostatectomies and preoperative PSA, histological grade, surgical margins, and extraprostatic extension: application of a new practical method for tumor extent evaluation. International Int Braz J Urol. 2003; 29: 113-20.

Dr. Athanase Billis
Full-Professor of Pathology
State University of Campinas, Unicamp
Campinas, São Paulo, Brazil