Objective: To determine the value of positive sextant biopsies in assessing
the location of prostate tumors within radical prostatectomy specimens and
to determine if prostate weight influences the results. Methods: From 1988
to 1996, 166 radical prostatectomies were performed for localized prostate
cancer diagnosed by means of ultrasound-guided sextant biopsies. The locat
ion of the biopsies was compared with that of tumor tissue within the radic
al prostatectomy specimen. Results: Of the 996 biopsies, 331 (33%) were pos
itive. The correspondence between the location of the biopsies and that of
tumor tissue in the surgical specimen was found to have a sensitivity of 39
.4%, a specificity of 81.5%, a positive predictive value of 83.3%, negative
predictive value of 36.4% and an accuracy of 52%. For prostates weighing <
and greater than or equal to 45 g, the sensitivity was 39.9 and 38.9%, the
specificity was 88 and 77.2%, the positive predictive value was 90.8 and 7
6.1%, the negative predictive value was 34.9 and 39.8%, and the accuracy wa
s 52 and 52%, respectively. Conclusion: Negative biopsies do not predict a
lack of tumor tissue in the corresponding prostate site after radical prost
atectomy, and had less value than positive biopsies for prognostic staging
before radical prostatectomy. Results of sextant biopsies are more signific
ant for prognosis before radical prostatectomy when positive. Prostate weig
ht influences the interpretation of the results of sextant biopsies.