To more clearly elucidate the relationship between prostate volume (PV) and prostate cancer parameters.

The Urologic Oncology Database was reviewed. A total of 3460 patients had undergone radical prostatectomy from 1988 to 2006. Of these, 2600 with complete data were included in the study and were stratified by the PV: normal (0 to 40 cm³), moderate (40 to 80 cm³), or large (greater than 80 cm³). The prostate cancer variables were evaluated using analysis of variance. Regression models were used to determine the role of PV in Gleason sum discordance (greater than 1 unit) controlling for prostate-specific antigen level and clinical and pathologic stage.

Of the 2600 patients, 1453 (55.2%) had a normal, 1035 (39.8%) a moderate, and 130 (5.0%) a large PV. Patients with a normal PV were more likely to have a Gleason sum greater than 6 at biopsy (46.2%) and radical retropubic prostatectomy (68.4%) compared with patients with a moderate (39.0% and 58.9%, respectively) or a large (41.5% and 57.7%, respectively) PV (P = 0.005 and P = 0.001, respectively). Patients with a normal PV had greater rates of extraprostatic extension (32.3%) and positive margins (28.2%) compared with those with a moderate (25.5% and 22.4%, respectively) or a large (23.3% and 20.3%, respectively) PV (P = 0.002 and P = 0.005, respectively). Of all 2600 patients, 55.9% had no change between the biopsy and pathologic Gleason sum, 255 (9.8%) were downgraded, and 890 (34.3%) were upgraded. Patients with a large PV had a greater rate of downgrading (16.2%) than those with a normal (8.7%) or moderate (10.5%) PV (P = 0.01). Patients upgraded had the greatest rate of pathologically advanced disease (35.3% with Stage T3 or greater, P <0.001). On multivariate regression analysis, PV (odds ratio 0.99, P = 0.005), prostate-specific antigen level (odds ratio 1.03, P <0.001), and age (odds ratio 1.03, P <0.001) were predictors of Gleason discordance ±2.

The results of our study have shown that patients with a large PV (greater than 80 cm³) are more likely to have a lower Gleason sum, locally confined and less-aggressive pathologic disease, and were more often downgraded.