Transperineal Prostate Biopsy Trumps TRUS
Shady Nafie, MRCS
Transperineal template prostate biopsy (TPTPB) identifies tumors of a smaller size and earlier stage than transrectal ultrasound (TRUS)-guided biopsy, suggesting that TPTPB may be a far more ideal diagnostic test for localized prostate cancer (PCa), researchers reported online ahead of print in the World Journal of Urology.
Shady Nafie, MRCS, of the Department of Urology at Leicester (U.K.) General Hospital and colleagues. As Nafie and his team noted in their report, the possibility of PCa as a cause for steadily rising PSA levels despite previously negative TRUS-guided prostate biopsies is a major concern. After reviewing the records of 122 men who had undergone 36-core TPTPB following two previous sets of negative TRUS-guided biopsies despite raised PSA levels, the researchers made a retrospective record of PSA levels, clinicopathologic parameters, and histologic outcomes.
The patients, aged 49-77 years (mean age 63 years), had a mean PSA level of 18.0 ng/mL (range 2.0-119.0 ng/mL) at the time of TPTPB. This was higher than the mean PSA level of 14.0 ng/mL (range 1.4-122.0 ng/mL) at the time of previous TRUS-guided biopsy. An average of 24 months (range 2-228 months) had elapsed between the last TRUS-guided biopsy and the TPTPB, with mean PSA velocity of 2.3 ng/mL per year (range 0 to 33.6 ng/mL).
More than half the men (71, or 58%) received a diagnosis of prostate cancer on TPTPB:
· 28 (39%) had a Gleason score of 6
· 34 (48%) had a Gleason score of 7 (3 + 4)
· 5 (7%) had a Gleason score of 7 (4 + 3)
· 4 (6%) had a Gleason score of 9 (4 + 5).
The mean number of positive cores was 7 (range 1–22), with only 15 men (21%) having three or less positive cores and a Gleason score of 6. As seen in previous studies, a high proportion of cancer-containing biopsies were located in the anterior zone of the prostate, with nearly 50% of cancer-containing cores found in that region. Nafie's group pointed out that because the anterior zone of the prostate is poorly sampled during TRUS-guided biopsy, the high proportion of anterior tumors is to be expected. However, despite the fact that TRUS-guided biopsy is able to sample posterior tumors adequately and all patients had had two previous sets of TRUS-guided biopsies, a substantial number of prostate cancers (20%) identified on TPTPB were located in the posterior zone of the gland.
Of the 51 men (42%) with a nonmalignant diagnosis on TPTPB, 11 (22%) had atypical small acinar proliferation, 10 (19%) had high-grade prostatic intraepithelial neoplasia, and 30 (59%) had benign pathology.
The investigators found no significant difference in mean PSA levels at the time of TPTPB between the men diagnosed with PCa (20.2 ng/mL) and those with noncancer histology (14.9 ng/mL). The two groups also did not differ significantly in mean PSA velocity, which was 2.9 ng/mL per year for the men with a malignant pathology and 1.1 ng/mL per year for those without.
The investigators concluded that TPTPB should be regarded as the gold-standard test in men with two sets of negative TRUS-guided biopsies and rising PSA levels, and that consideration must be given to performing TPTPB in men with one negative TRUS biopsy in whom cancer is suspected.