Objectives: To more clearly elucidate the relationship between prostate volume (PV) and prostate cancer parameters. Methods: 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. Results: 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. Conclusions: 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.
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