Prostate cancer detection rate in patients with repeated extended 21-sample needle biopsy

Abstract

Background: Prevalence of prostate cancer (PCa) after a negative first extended prostate needle biopsy protocol is unknown.

Objective: To evaluate the prevalence of significant PCa in patients who have had a negative first extended prostate biopsy protocol.

Design, setting, and participants: Between March 2001 and May 2007, 2500 consecutive patients underwent an extended protocol of 21 biopsies. Of 953 patients who had a negative first extended prostate biopsy procedure, 231 patients underwent a second or more set of 21-core biopsies. Indications for repeated biopsies were persistently elevated prostate-specific antigen (PSA), PSA increase during the follow-up, or prior prostatic intraepithelial neoplasia (PIN), or atypical small acinar proliferation (ASAP).

Intervention: All participants underwent at least two extended prostate needle biopsy protocols.

Measurements: Clinical and pathologic factors (age, PSA, PSA doubling time, PIN, ASAP, digital rectal exam [DRE]) were analyzed for their ability to predict positive biopsy, and tumour parameters were assessed in patients undergoing radical prostatectomy.

Results and limitations: Second, third, and fourth extended 21-sample biopsy procedures yielded a diagnosis of PCa in 18%, 17%, and 14% of patients respectively. Patients with prior PIN had 16% risk of prostate cancer; patients with ASAP had a 42% risk. The mean number of positive cores was 2.19. Prostate volume and PSA density were statistically significant predictors of positive biopsy (p<0.05). For the 43 patients who underwent radical prostatectomy, pathologic findings revealed mean Gleason score of 6.7 (6-8), pT2a-c in 72%, pT3a in16%, and pT4 in 7%. Mean cancer volume was 1.15 cc and 85.2% of tumours were clinically significant (tumour volume > 0.5 cc, Gleason > or = 7 and/or pT3).

Conclusions: Negative first extended biopsies should not reassure a patient of not having PCa. However, prostate cancers detected after two or more sets of extended procedures, appear to be localized (intracapsular disease) and well-differentiated prostate cancers, although they are still clinically significant.