Use of effective core volume obtained from transrectal biopsies for predicting target tumor volume

Abstract

Objectives To evaluate, in a retrospective review, whether the concept of effective core volume is useful for predicting the volume of a tumor focus identified by transrectal needle biopsy of the prostate gland. Methods The tumor volume range was estimated according to the concept of an effective core volume using the numbers of total and positive biopsy cores from the peripheral zone and peripheral zone prostate volume in 32 patients with prostate cancer with one to three cancer-positive cores who only underwent radical prostatectomy after transrectal prostate biopsy. The estimated tumor volume was compared with the actual tumor volume as determined by pathologic examination of whole mount sections of the prostatectomy specimens. Results In the 32 patients, the actual tumor volume was within the range determined by the effective core volume concept in 24 patients (75.0%), although 4 (12.5%) had a smaller focus and 4 (12.5%) a larger focus than estimated. Overall accuracy improved up to 84.4% (27 of 32) if 5% safety margins were applied to the range determined by the effective core volume concept. In particular, the accuracy was 87.5% (14 of 16) in patients with one positive core after transrectal systemic biopsy. Conclusions The effective core volume can be used to predict the volume of prostate cancer with acceptable accuracy. It can provide an assumed maximal tumor volume and valuable information for clinical decision making of the treatment strategy, particularly in cases with one positive core.