Internal prostatic architecture on transrectal ultrasonography predicts future prostatic growth: natural history of prostatic hyperplasia in a 15-year longitudinal community-based study.

BACKGROUND

From 1992 to 1993, we conducted a cross-sectional community-based study to clarify the prevalence of benign prostatic hyperplasia in Japanese men aged 40-79. Based on the results, we hypothesized that the internal prostatic architecture (IPA) on transrectal ultrasonography (TRUS) would predict future prostatic growth. We investigated the changes in prostate volume (PV) over time and validated our hypothesis on predictors for future prostatic growth.

METHODS

Of 319 participants in the initial study, the PV of 104 men was evaluated by TRUS with approximately a 15-year follow-up in the current study. We categorized prostates into three groups based on the IPA: group 1, invisible transition zone (TZ); group 2, visible TZ with an unclear border; and group 3, visible TZ with a clear border.

RESULTS

Overall PV significantly increased from 17.4  ml to 23.9  ml (P  <  0.001). The median PV changes by age decade (40s, 50s, 60s, and 70s) were 5.5, 5.6, 8.6, and 11.1  ml, respectively. Those by baseline PV < 20  ml, 20-25  ml, and ≥ 25  ml were 5.3, 9.8, and 14.7  ml, respectively. Those by baseline IPA for group 1, group 2, and group 3 were 4.7, 6.5, and 17.3  ml, respectively. Multiple linear regression analysis indicated that PV (P  =  0.027) and the IPA (P  <  0.001) at baseline were independent predictors for future prostatic growth.

CONCLUSIONS

This was the first study by longitudinal community-based study that the PV in Japanese men increased during 15 years. The IPA on TRUS is useful for predicting future prostatic growth.