Purpose: The 5 region method of prostate biopsy takes standard sextant biopsies and additional systematic biopsies of the far lateral and middle aspects of the prostate gland. This method has been shown to increase the cancer detection rate of prostate biopsy by 35% over the standard sextant biopsy method, and it is most effective in patients with prostate specific antigen less than 10. Concern has arisen that by taking additional biopsies, cancers are being detected which would otherwise be clinically insignificant. We compare pathological findings of radical prostatectomy specimens detected by the 5 region and sextant biopsy methods to determine if there is a significant difference between tumors diagnosed by each method.
Materials and methods: A total of 21 patients enrolled in the 5 region prostate biopsy study with biopsy proved prostate cancer underwent radical prostatectomy. Prostatectomy specimens of 5 zone detected cancers in 11 cases were compared to sextant method detected cancer in 10. Radical prostatectomy specimens were analyzed for tumor volume, ploidy status, Gleason score and TNM pathological stage. Tumor volumes were determined by point counting morphometric analysis using an overlying grid. Tumor ploidy status was determined by deoxyribonucleic acid (DNA) image analysis.
Results: Mean tumor volume was 2.4 cc (range 0.10 to 9.6, median 1.4) for 5 region detected cancers versus 1.9 cc (range 0.10 to 6.1, median 1.0) for sextant method detected cancers. This difference was not statistically significant (p = 0.643). Mean DNA index was 1.1 (range 0.93 to 1.64) for 5 region detected cancer compared to 1.4 (range 0.96 to 2.2) for sextant method detected cancer. Overall there were 8 diploid tumors and 3 aneuploid tumors in the 5 region group compared to 4 diploid tumors and 6 aneuploid tumors in the sextant group. Mean Gleason scores were not significantly different for the 5 region (6.5) and sextant (6.7) groups (p = 0.672). Final tumor stage for the 5 region group was 4 pT3 (36%) and 7 pT2 (64%) tumors compared to 2 pT3 (20%) and 8 pT2 (80%) tumors for the sextant group.
Conclusions: Our data demonstrated no significant difference in tumor volume, DNA ploidy status, Gleason score or final pathological tumor stage between tumors diagnosed using the 5 region versus sextant biopsy techniques.