Increasing the number of biopsies increases the concordance of Gleason scores of needle biopsies and prostatectomy specimens

Abstract

Purpose To determine the importance of increasing the number of biopsy cores to decrease the discrepancy of Gleason scores of needle biopsy and radical prostatectomy specimens. Materials and methods Between May 1998 and July 2005, 392 patients with clinically localized prostate cancer diagnosed by 18-gauge transrectal needle biopsy underwent radical prostatectomy. We categorized the cohort into 2 groups according to the number of the cores. Group 1 consisted of 206 patients diagnosed by extended biopsies (≥10 cores, range 10–14, median 11). The remaining 186 patients who were diagnosed by sextant biopsies were categorized as being in group 2. Preoperative clinical variables, including patient age, digital rectal examination findings, serum prostate-specific antigen, and the number of cores positive for cancer the parameters, were assessed in both groups. The concordance of Gleason scores in both groups were analyzed by both individual Gleason scores and clinical subgroups of Gleason scores: 2–4 (well differentiated), 5–6 (moderately differentiated), 7 (intermediate), and 8–10 (poorly differentiated). Results Needle biopsies revealed moderately differentiated tumors (Gleason 5–6) for the 2 groups (55.3% and 60.2%). Gleason scores of the needle biopsies were identical to that of the prostatectomy specimen in 116 (56.31%) and 76 cases (40.86%) for each group (kappa: 0.432 and 0.216 for each group, respectively). Gleason score of the needle biopsy differed by 1 grade in 56 (27.18%) and 84 cases (45.16%), and by ≥2 units in 34 (16.50%) and 26 cases (15.05%) for each group, respectively. Of the specimens, 34% were undergraded, and 10% were overgraded in group 1. These rates were 38% and 22% in group 2, respectively. A total of 70% in group 1 and 56% in group 2 remained in the same categorical group, 28% and 32% of the specimens were undergraded, and 4% and 12% were overgraded in groups 1 and 2, respectively. In group 1, the number of patients with Gleason scores of 2–4, 5–6, 7, and 8 were 9.7%, 55.3%, 21.4%, 13.6%, and 1.9%, 47.6%, 32%, 18.4%, graded by needle biopsies and radical prostatectomy specimens, respectively. However, in the sextant group, the change was the number of patients with Gleason scores of 2–4, 5–6, 7, and 8–10 was 5.4% 60.2%, 24.7%, and 9.7%, detected by needle biopsies, respectively. Radical prostatectomy specimens revealed the same Gleason categories in 4.3%, 41.9%, 38.7%, and 15.1%, respectively. There was no correlation between categorized prostate-specific antigen levels and concordance of the Gleason grade. Age and digital rectal examination results did not affect Gleason correlation. Conclusions We have shown that an extended biopsy scheme beyond its superior diagnostic capability also improves the concordance of Gleason scores of needle biopsies and radical prostatectomy specimens.