The significance of prostatic intra-epithelial neoplasia

To investigate the relationship between the detection of prostatic intra-epithelial neoplasia (PIN) on initial prostate biopsy and subsequent invasive prostatic adenocarcinoma.

Thirty-six men (mean age 67 years, range 52-82) with PIN underwent digital rectal examination (DRE), serum prostate-specific antigen (PSA) measurement and transrectal ultrasonography (TRUS) before the initial biopsy and documentation of PIN. They were followed up with serial PSA, TRUS and a repeat biopsy every 6 months until either invasive carcinoma was identified or 2 years had elapsed.

The initial biopsy revealed Grade I PIN in 33%, Grade II in 22%, and Grade III in 45% of the men. The repeat biopsy showed evidence of invasive carcinoma in 21 patients (58%; Group I), while 15 (42%) showed persistence of PIN (Group II). In Group I, 19 had had high-grade PIN (Grade II/III) on initial biopsy compared with one in Group II. The findings on DRE, and age, were no significantly different between groups. TRUS revealed a hypoechoic lesion in 15/21 patients in Group I compared with 7/15 patients in Group II. There was an increase in PSA level in 18 patients in Group I (from 8.4 to 11.6 ng/mL).

PIN and invasive adenocarcinoma of the prostate were closely associated, and the likelihood for coexistence was higher in patients with high-grade PIN, increasing PSA level or positive findings on TRUS. We recommend that all patients who show high-grade PIN on prostate biopsy be followed very closely with serial PSA measurements and repeat biopsies from both the area of PIN and other areas of the prostate.