Extent and zonal distribution of prostatic intraepithelial neoplasia in patients with prostatic carcinoma in Japan: analysis of whole-mounted prostatectomy specimens

BACKGROUND: Prostatic intraepithelial neoplasia (PIN), an intraluminar proliferation of epithelial cells in ducts and acini, is divided into high-grade (HGPIN) and low-grade (LGPIN), based on morphologies. HGPIN is considered to be a putative precursor of prostatic adenocarcinoma (PCA). Information on PIN has been limited in Japan, because PIN had not been regarded as a precursor lesion for PCA. METHODS: In this study, extent and zonal distribution of PIN together with its relationship with PCA were examined in totally embedded radical prostatectomy specimens obtained from 70 patients with PCA. Fifty-three patients received androgen deprivation therapy (castrated) and remaining 17 did not (noncastrated). RESULTS: Frequency of HGPIN in noncastrated cases (76%) was much higher than that in castrated cases (26%) (P < 0.001). LGPIN showed the same tendency, but the difference was smaller. Difference in mean number of HGPIN in noncastrated and castrated cases (12.0 and 6.4, respectively) was more marked than in LGPIN (6.4 and 5.1, respectively). Reduction rate of mean size in HGPIN (26%) by the androgen deprivation therapy was larger than in LGPIN. When evaluated in noncastrated cases, the coexistence of PCA and HGPIN was found in 76% of cases in the nontransition and 53% in the transition zone. Close association of PCA and PIN (