Purpose: 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.
Methods: 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).
Results: 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.
Conclusions: 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.