ESTIMATION OF PROSTATE-CANCER VOLUME BY MULTIPLE CORE BIOPSIES BEFORERADICAL PROSTATECTOMY

Objectives. To investigate whether tumor volume, an important prognost ic factor in prostate cancer, could be estimated from the amount of ca ncer in multiple core biopsies. Methods. In 80 men, transrectal ultras ound-guided biopsies were taken from focal lesions detected by ultraso und and 8 to 10 standardized positions, including sextant biopsies (ap ex, midmedial, base) and midlateral and transition zone biopsies. The cancer length in the biopsies was measured. After radical prostatectom y, the prostates were totally embedded, whole-mounted, and tumor volum e was measured planimetrically. Results. The tumor volume correlated s ignificantly with the total cancer length of all biopsies (r = 0.56) a nd of the sextant biopsies (r = 0.39). It was found that midlateral an d transition zone biopsies provided independent information when inclu ded in a multiple regression model with tumor volume as the dependent variable and the sextant biopsies as explanatory variables. All men (n = 6) with less than 3 mm cancer length in only one positive biopsy an d a Gleason score less than 7 had a tumor volume less than 1 mt. Nine of 10 men with less than 7 mm of cancer in one positive biopsy and Gle ason score less than 7 had tumors smaller than 1 mt. Sextant biopsies did not reliably predict cancer volumes less than 1 mt. Conclusions. T he cancer yield of 8 to 10 biopsies correlated better with the volume of prostate cancer than sextant biopsies. This extended biopsy protoco l could be used to predict cancers of less than 1 mt in volume. UROLOG Y 52: 655-658, 1998. (C) 1998, Elsevier Science Inc. All rights reserv ed.