Identification of Candidates for Radical Prostatectomy with TPMB

San Diego—The identification of men with prostate cancer who are best suited for radical prostatectomy may be aided by use of intra-prostatic staging by transperineal mapping biopsy (TPMB). E. David Crawford, MD, and colleagues recently conducted an analysis of transrectal ultrasonography (TRUS) biopsy positive men with minimal disease, biopsy negative, and biopsy naïve men who had TPMB followed by radical prostatectomy. The researchers reported results of the analysis at the AUA 2016 Annual Meeting in a presentation titled Transperineal Prostate Mapping Biopsy Correctly Identifies Candidates for Radical Prostatectomy.

A cohort of 366 men who were being considered for focal therapy or active surveillance had TPMB. Of those, 45 of 218 (20.6%) with prostate cancer had radical prostatectomy; 12 (26.7%) had a prior positive TRUS biopsy with minimal disease, 24 had negative biopsy, and nine were biopsy naïve. TPMB was performed through a template with biopsies taken at intervals of 5 mm. If prostate length exceeded 2 cm, multiple in-line samples were taken. Biopsy locations were tracked using a proprietary software program.

Men with prior TRUS had a median of 12 cores sampled; the 45 men with TPMB had 50 cores. ANOVA and chi-square analysis were used to compare associations between positive TRUS and TPMB in men undergoing radical prostatectomy. The results of TPMB were also compared to the surgical pathology specimen.

Median age of the cohort was 63 years, median PSA was 6.3 ng/mL, and PSA density was 0.164. Six of the 12 men with positive biopsy had Gleason score 6 and six had Gleason score 7. Of those 12 men, TPMB revealed Gleason score 3 in three (25%), Gleason score 7 in seven (58.3%), and Gleason score 8-10 in two (16.7%). The median number of positive cores was 12 and 14 patients (58.3%) had bilateral disease. Radical prostatectomy specimens revealed Gleason score 6 in two patients, Gleason score 7 in seven, with three pending.

Following radical prostatectomy, eight patients had pT2c and one had pT3. None of the patients were downgraded to low volume Gleason score 6. Thirty-three had negative TRUS biopsy or were biopsy naïve and had TPMP followed by radical prostatectomy.

Mapping pathology was Gleason score 6 in 11 patients (33%), Gleason score 7 in 17 patients (51.5%), and Gleason score 8-10 in five patients (15.5%). Bilateral disease was present in 22 patients (66.7%). Surgical specimen data was available in 25 of the patients (six with Gleason score 6, 16 with Gleason score 7, and four with Gleason score 8-10. Radical prostatectomy stage was pT2a/b in four patients, pT2c in 13 patients, and pT3 in eight patients. The two patients with low volume disease on radical prostatectomy each had one core Gleason score 6 with TPMB.

“Intra-prostatic staging by TPMB can correctly identify appropriate candidates for radical prostatectomy. Forty-three of 45 (95.6%) had high volume or grade on surgical pathology which was determined by TPMB. The two radical prostatectomy patients who could have been managed by active surveillance were also identified by mapping biopsy,” the researchers said.

Source: Crawford, E D, Skouteris V, Arangua P, Stone N. Transperineal prostate mapping biopsy correctly identifies candidates for radical prostatectomy. Abstract of a presentation at the American Urological Association 2016 Annual Meeting, May 8, 2016, San Diego, California.