Transitional Zone and Anterior Peripheral Zone of the Prostate

Abstract

Introduction: Prognostically significant prostatic adenocarcinomas (PAC) may pose diagnostic problems if they were localized in the anterior peripheral zone (APZ) or transitional zone (TZ). Materials and Methods: 108 cases of PAC were reviewed along with serum PSA and TRUS biopsies. The PACs were divided into 22 TZ, 17 APZ and 69 posterior peripheral zone (PPZ) PACs according to the location of the main tumor mass in the TZ and anterior or posterior half of the peripheral zone in the radical prostatectomy (RP) specimens. Results: In comparison with PPZ PAC, TZ PAC had a higher cancer volume in RP specimens (4 ± 2.1 vs. 2.5 ± 1.7 cm³, p < 0.01), a higher serum PSA (16.5 ± 9.8 vs. 8.4 ± 4.5 µg/l, p < 0.001), a biopsy with a small cancer volume (3.8 ± 2.1 vs. 11.8 ± 9.4 mm, p < 0.005), and a lower Gleason’s score (4.8 ± 2.1 vs. 6.5 ± 1.7). APZ PAC was characterized by the cancer volume in RP and biopsy and PSA intermediate between those of TZ and PPZ PAC. Among 24 PACs with a total cancer core length of <3 mm, 19 cases were from the TZ and APZ groups and also had a higher cancer volume and PSA than those from the PPZ group (2.9 ± 1.8 vs. 1.5 ± 1.3 and 13.7 ± 8.3 vs. 9.6 ± 4 µg/l, respectively). Furthermore, there was a better correlation coefficient (r²) of tumor volume in the biopsy and RP for PPZ than for all zones PAC (r² = 0.75 vs. 0.29). TZ and APZ carcinomas were associated with extension or satellite nodules of PAC in the PPZ that may be diagnosed with biopsies. These PACs were associated with positive anterior resection margin due to extracapsular extension of the carcinoma or intracapsular dissection in 6 and 5 cases respectively. Conclusions: TZ and APZ PACs accounted for the poor correlation between the tumor volume in the biopsy and the RP, and were associated with positive anterior resection margins. One core biopsy with a total cancer core length of <3 mm and PSA >10 µg/l are suspicious for TZ and APZ PCA in patients with undetectable tumors with DRE or TRUS. Clinically insignificant PACs tend to be associated with cancer core <3 mm and PSA <10 µg/l.