Objectives: The number of cores obtained during transrectal ultrasound-guided prostate biopsy to detect cancer has increased from the previous standard of 6. Increasing the number of biopsy cores taken results in a higher prostate cancer detection rate. Because criteria for defining the clinical significance of localized prostate cancer has been proposed, the question may be asked whether the increased number of tumors found is clinically significant.
Methods: The Urology Service's surgical log database revealed 369 patients who underwent radical prostatectomy as primary therapy between January 1997 and March 2001. Only men who had had more than six core biopsies that included the standard sextant and lateral horns of the peripheral zone biopsies were considered. The hospital's clinical information system was then used to extract all additional data for age, clinical stage, pretreatment prostate-specific antigen level, and transrectal ultrasound-guided biopsy and subsequent whole mount pathology results, including pathologic stage, number of tumors, largest single and aggregate tumor volumes, highest tumor Gleason score, and tumor locations. A total of 127 men comprised our final group.
Results: Subgrouping based on the location of positive biopsy results yielded 40 (31.5%) in the standard sextant biopsy only, 31 (24.4%) in the lateral horns of the peripheral zone only, and 56 (44.1%) of 127 tumors in both zones. The Gleason score was similar throughout. The margin-positive rate was 12.5% for the sextant-only positive biopsies, 12.9% for the lateral horn-only positive biopsies, and 42.9% for the both positive biopsies. The insignificant tumor rate for the group as a whole was 5.5% (7 of 127). The insignificant tumor rate for the lateral horn-only positive biopsies was 3.2% (1 of 31).
Conclusions: The addition of laterally directed biopsies increases the rate of prostate cancer detection, and the vast majority of these tumors are clinically significant.