Prostate cancer detection rates in different biopsy schemes. Which cores for which patients?

To determine whether the addition of four paramedian peripheral and four lateral peripheral cores improves the cancer detection rate (CDR) of the extended 10-core biopsy scheme and which patients benefit most from such additional samples.

One thousand and ninety-one consecutive patients scheduled for first ultrasound-guided transrectal prostate biopsy prospectively underwent a 18-core biopsy scheme, including the traditional sextant (6-core), 4 lateral peripheral (10-core), 4 paramedian peripheral (14-core) and additional 4 lateral peripheral cores (18-core).

The CDR of the 6-, 10-, 14- and 18-core schemes was 33.1, 39.2, 41.6 and 41.8 %, respectively; the difference between the 10- and 6-core scheme reached significance (p < 0.005), whereas that between the 18- or 14- and the 10-core scheme did not. The percentage of tumors diagnosed on the sole basis of the 14-core scheme was significantly greater in patients with low PSA (≤ 7.2 vs. >7.2 ng/ml: 12.1 vs. 1.8 %; p < 0.0001), large prostate volume (≥ 50 vs. <50 cc: 3.4 vs. 9.1 %; p = 0.011) and particularly low PSA density (<0.15 vs. ≥ 0.15: 15.9 vs. 1 %; p < 0.0001). The 18-core scheme did not provide diagnostic advantages in any patients' population.

The addition of 4 lateral peripheral samples did not increase the CDR of the 10-core biopsy scheme. The addition of four paramedian peripheral samples was beneficial only in patients with PSA density <0.15, in whom the 10-core scheme would have miss almost 16 % of tumors. Since more than half of our patients had low (<0.15) PSA density, these findings seem to be of great clinical relevance.