Are transrectal prostate biopsies routinely indicated in patients with incidentally diagnosed prostate cancer following transurethral resection of the prostate for benign disease?

OBJECTIVE To determine the indication of routine transrectal ultrasound-guided needle biopsy (TRUSBx) of the prostate gland following incidental cancer diagnosis after transurethral resection of the prostate (TURP) for benign prostatic hyperplasia. MATERIALS AND METHODS A multi-institutional search identified 63 patients with incidental TURP-diagnosed prostate cancer from 2001 to 2010, who underwent subsequent TRUSBx or radical prostatectomy (RP). The Gleason scores from TURP were compared to those from TRUSBx or RP. Whole mount maps from RP were analysed to provide an anatomical basis for the correlation observed. To determine the clinical impact of this problem, the incidence of TURP-diagnosed prostate cancer in the population was also determined. RESULTS Of 22 patients who underwent TRUSBx, the rates of Gleason score concordance, upgrading and downgrading were 32, 14 and 54% respectively (Spearman correlation coefficient 0.20). Most cases of pathological downgrading consisted of benign cores at biopsy. Therefore, TRUSBx did not give additional Gleason score (GS) information in 86% of patients. Of 41 RP patients, the respective rates were 61, 22 and 17% (Spearman correlation coefficient 0.15). The majority of them retained a similar or lower GS between TURP and RP. Of 13 whole mount maps analysed, 6 (46%) were found with anterior/transitional zone (AZ/TZ) tumours, 6 (46%) with multifocal tumours and 1 (8%) with a large peripheral zone (PZ) tumour extending into the TZ. Regional population data show that despite a gradual reduction in the proportion of TURP-diagnosed cases over the past decade, they still account for 8.5-13% of all new cases. CONCLUSION TURP-diagnosed prostate cancers represent predominantly AZ tumours. A TRUSBx does not give additional GS information in a majority of cases, and therefore is not routinely indicated. It may be selectively useful prior to active surveillance, but not in all pursuing radical treatment. These findings may help reduce unnecessary TRUSBx in the population.