Individualization of the biopsy protocol according to the prostate gland volume for prostate cancer detection.

PURPOSE

In this study we assessed the relative yield of 10 core biopsy, and the whole range of alternative 8 and 6 core biopsy protocols over that of the classic sextant biopsy protocol. We determined the optimum number of cores per biopsy according to prostate volume in patients who experienced prostate biopsy for the first time.

MATERIALS AND METHODS

A total of 503 men with the indications of abnormal digital rectal examination and/or serum prostate specific antigen greater than 2.5 ng/ml were included in the study. All patients underwent a 10 core biopsy protocol with an additional 1 core from each suspicious area detected by transrectal ultrasound. Prostate volume was divided into quartiles, namely 14.9 to 35, 35.1 to 50, 50.1 to 65 and 65.1 to 150 cc. The optimum number of biopsy cores was determined in patients with different prostate volumes.

RESULTS

Median age was 63 years and prostate specific antigen was 7.4 ng/ml in the whole group. Of 503 patients 159 (31.6%) were positive for prostate cancer. Cancer detection rates decreased significantly from 49.6% to 20.8% as prostate volume increased in preset quartiles. Lesion biopsies revealed the lowest unique cancer detection rates for all prostate volume quartiles (0% to 3%). There was an obvious positive trend in cancer detection rates in favor of the 10 core biopsy protocol over sextant biopsies in all patient groups. Classic sextant biopsy protocol proved to be inadequate for all prostate volumes. Among sextant biopsy protocols laterally placed cores including the apex, lateral mid gland and lateral base had the best cancer detection rates (81% to 95%). The 8 core biopsy scheme consisting of the apex, mid gland, lateral mid gland and lateral base resulted in an only 1% lower detection rate (97%) than the 10 core biopsy protocol in the lowest quartile. The yield of the 10 core biopsy protocol in patients with a prostate volume of between 35.1 and 150 cc outscored that of the optimal 8 core biopsy scheme including the apex, base, lateral mid gland and lateral base with 3% to 8% differences in the cancer detection rate.

CONCLUSIONS

The 10 core biopsy protocol must be used in all group of patients except patients with a prostate volume of 14.9 to 35 cc. In patients with a prostate volume of 14.9 to 35 cc the 8 core biopsy protocol consisting of the apex, mid gland, lateral mid gland and lateral base can be used since it revealed results similar to those of the 10 core biopsy protocol. The classic sextant biopsy protocol seemed inadequate for all prostate volumes. Patients with a larger prostate had lower cancer detection rates. Transrectal ultrasound directed lesion biopsies may be omitted when using 10 core biopsy protocols since the yield of these biopsies was less than 2%.