SEXTANT PROSTATE BIOPSIES - A HISTOPATHOLOGIC CORRELATION WITH RADICAL PROSTATECTOMY SPECIMENS

Background. Among patients with clinically localized prostate cancer, preoperative prediction of tumor volume and pathologic stage has been unreliable. This study examines the application of transrectal ultraso und-guided sextant biopsies to predict the extent of disease. Methods. One hundred and two patients with clinically resectable prostate canc er were evaluated by systematic sextant biopsies. Radical prostatectom y specimens were embedded totally as whole mounts, tumor areas were ou tlined, and volume was measured using a digital scanner. The number of positive sextant biopsies was compared with age, race, preoperative p rostate specific antigen (PSA), PSA density, DNA ploidy, pathologic st age, capsular and seminal vesicle involvement, prostate and tumor volu me, and Gleason score. Stepwise logistic regression was used to determ ine if pathologic stage or tumor size could be predicted by these para meters. Results. The number of positive sextant biopsies correlated wi th traditional prognostic indicators. When patients with three or fewe r positive biopsies were compared with those with four or more positiv e sextant biopsies, significant differences were identified relative t o preoperative PSA (P < 0.001), tumor volume (P < 0.001), pathologic s tage (P < 0.001), Gleason score (P < 0.001), seminal vesicle involveme nt (P < 0.001), and capsular penetration (P < 0.001). There were no si gnificant differences based on age, race, DNA ploidy, and overall pros tate volume. Logistic regression showed that patients with four or mor e positive sextant biopsies and high Gleason score had a greater likel ihood of pT3 classification. Likewise, the probabilities of a tumor vo lume less than 0.5 ml could be predicted by the number of positive sex tant biopsies and PSA alone. The number of positive sextant biopsies w as the only factor that could predict a tumor volume greater than 4.0 ml. Conclusion. The number of positive sextant biopsies appears to be an important prognostic indicator of pathologic (pT) classification an d tumor volume. This information is valuable in selecting the treatmen t strategy for patients with prostate cancer.