Prospective evaluation of systematic sextant transition zone biopsies in large prostates for cancer detection

A prospective evaluation was performed to define the role of systematic transition zone (TZ) biopsies in prostates larger than 50 cc.

From August 1994 to July 1997, 213 consecutive patients referred because of an abnormal digital rectal examination or prostate-specific antigen greater than 4.0 ng/mL had a calculated prostate size greater than 50 cc by transrectal ultrasound (TRUS) measurement. These patients underwent TRUS-guided sextant biopsies of the peripheral zone (PZ) and TZ.

The median calculated prostate size was 70 cc with a TZ size of 39 cc. Fifty-five cases of carcinoma of the prostate were found, giving a 26% detection rate. The TZ biopsies detected cancer in 30 of the 55 patients (55% sensitivity) compared with the 47 patients detected by the PZ biopsies (85% sensitivity). Seven cancers (13%) were detected only by the additional TZ biopsies. TZ biopsies revealed bilateral tumors when the PZ biopsies had shown unilateral disease in 2 cases. In 6 cases the TZ biopsies showed higher Gleason grade tumors than was found in the PZ. In the 30 cases with positive TZ biopsy, concordance between the PZ and TZ biopsies occurred in 74% (133 of 180) of the sectors. The PZ biopsy detected cancer in 43 of 66 corresponding sectors that had positive TZ biopsies, giving a sensitivity of 65% and a negative predictive value of 80%.

Routine PZ biopsies missed detecting 13% of the cancers found with the addition of sextant TZ biopsies in patients with large prostates (greater than 50 cc). In addition, 14% of the patients with cancer had upgrading or detection of bilateral tumor with the added biopsies. Routine systematic sextant TZ biopsies should be considered in patients with prostates greater than 50 cc in size.