Diagnosis of high-grade prostatic intraepithelial neoplasia: the impact of the number of biopsy cores at initial sampling on cancer detection after a saturation re-biopsy

Objectives: To evaluate factors that may predict prostate cancer (PCa) detection after initial diagnosis of high-grade prostatic intraepithelial neoplasia (HGPIN) on 6-24 cores prostatic biopsies (PBx). Material and Methods: We retrospectively evaluated 193 patients submitted from 1998 to 2007 to prostate re-biopsy after initial HGPIN diagnosis in three urologic departments. HGPIN diagnosis was obtained on initial systematic PBx with 6 to 24 random cores. All patients were re-biopsied with a "saturation" PBx with 18-26 cores with a median time to re-biopsy of 12 months. All slides were reviewed by expert uro-pathologists. Results: Plurifocal HGPIN (pHGPIN) was found in 103 patients and monofocal HGPIN (mHGPIN) in 90. Seventy-two and 121 patients were submitted to > 12-core initial biopsy and ≤ 12-core, respectively. Overall PCa detection at re-biopsy was 28.4%. PSA (6.7 vs 8.5 ng/ml; p = 0.029) and age (64 vs 68 years; p = 0.005) were significantly higher in patients with PCa at re-biopsy. PCa detection was significantly higher in patients who underwent a ≤ 12-core initial PBx than in those with > 12-core (35.5% vs 16.8%; p = 0.03), and in patients with pHGPIN than in those with mHGPIN (34.9% vs 21%; p = 0.035). At multivariable analysis, PSA value (p = 0.007; HR:1.18), prostate volume (p = 0.01; HR:0.966), age (p < 0.001; HR:1.15), pHGPIN (p = 0.003; HR:2.97) and ≤12-core initial biopsy (p = 0.012; HR:3.62) were independent predictors of PC detection. We further analysed the 2 groups of patients submitted to ≤ 12-core and > 12-core initial PBx. Plurifocal HGPIN and older age at biopsy were independent predictors in patients with ≤ 12-core initial PBx. On the contrary, in patients with > 12-core initial biopsy, higher PSA values and lower prostate volume were independent predictors of PC detection. Conclusions: PCa detection on saturation re-biopsy after initial diagnosis of HGPIN is significantly higher in patients submitted to ≤ 12-core than those submitted to > 12-core initial PBx. In patients with ≤ 12-core initial biopsy pHGPIN and older age were predictors of PCa detection at re-biopsy. In patients with > 12-core initial biopsy, higher PSA values and lower prostate volume was associated to an increased risk of PCa detection at re-biopsy