Use of Extended Systematic Sampling in Patients With a Prior Negative Prostate Needle Biopsy

Abstract

We examine the potential impact of extended systematic biopsy schemes in patients with a prior negative prostate biopsy. Between January 1999 and March 2001, 185 patients with a prior negative prostate needle biopsy underwent repeat biopsy. Systematic 10 core biopsies (sextant, lateral mid gland and lateral base) were performed in all patients. A subset of 111 patients underwent 6 additional biopsies directed anteriorly. All biopsy results were reviewed by a single pathologist. The overall and unique cancer detection rates were calculated for each biopsy site. McNemar's test was then used to compare the yield of various simulated biopsy schemes to define the optimal biopsy regimen. Overall, 67 of 185 patients (36%) were found to have cancer on repeat biopsy. The highest detection rate was found for the apex, lateral base and lateral mid sites. The mid lobar base site consistently yielded the lowest detection rate. These results were mirrored in the unique cancer detection rate calculations. The traditional sextant scheme detected only 73% of tumors. Using a lateral sextant scheme (apex, lateral mid gland and lateral base), the detection rate increased to 85% (p = 0.15). An 8 core biopsy scheme (apex, mid gland, lateral mid gland and lateral base) increased the detection rate to 95%. However, there was no significant increase in cancer detection rate when the 8 core scheme was compared to the 10 core scheme. The 6 anteriorly directed biopsies uniquely detected only 2 cancers. We recommend that patients with a prior negative prostate biopsy who are undergoing repeat biopsy receive at least an 8 core biopsy scheme weighted toward the lateral aspect of the prostate.