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 ultrasound-guided sextant biopsies to predict the extent of disease.

METHODS

One hundred and two patients with clinically resectable prostate cancer were evaluated by systematic sextant biopsies. Radical prostatectomy specimens were embedded totally as whole mounts, tumor areas were outlined, and volume was measured using a digital scanner. The number of positive sextant biopsies was compared with age, race, preoperative prostate specific antigen (PSA), PSA density, DNA ploidy, pathologic stage, capsular and seminal vesicle involvement, prostate and tumor volume, and Gleason score. Stepwise logistic regression was used to determine if pathologic stage or tumor size could be predicted by these parameters.

RESULTS

The number of positive sextant biopsies correlated with traditional prognostic indicators. When patients with three or fewer positive biopsies were compared with those with four or more positive sextant biopsies, significant differences were identified relative to preoperative PSA (P < 0.001), tumor volume (P < 0.001), pathologic stage (P < 0.001), Gleason score (P < 0.001), seminal vesicle involvement (P < 0.001), and capsular penetration (P < 0.001). There were no significant differences based on age, race, DNA ploidy, and overall prostate volume. Logistic regression showed that patients with four or more positive sextant biopsies and high Gleason score had a greater likelihood of pT3 classification. Likewise, the probabilities of a tumor volume less than 0.5 ml could be predicted by the number of positive sextant biopsies and PSA alone. The number of positive sextant biopsies was 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 and tumor volume. This information is valuable in selecting the treatment strategy for patients with prostate cancer.