Differences in prostate size between patients from University and Veterans Affairs Medical Center populations.

Background: Numerous studies on prostatic disease have been performed at Veterans Affairs (VA) Medical Centers. Recent investigations evaluating early detection of prostate cancer provide insight that the average prostate volume may be different between patients with similar clinical findings who are from different hospital settings. The objective of this study was to compare prostate size between men from University and VA Medical Centers.
Methods: Patients were enrolled retrospectively from 1989-1996 from the Urology Clinics at a University and a VA Medical Center. All men underwent transrectal ultrasound-guided sextant biopsy of the prostate owing to either an elevated prostate-specific antigen (PSA) level and/or abnormal digital rectal examination (DRE) detected prior to biopsy. Prostate volume was calculated using the ellipsoid three-diameter formula based on transrectal ultrasound measurements.
Results: There were 1,311 men included in the analysis: 717 were from the VA, and 594 were from the University. The average prostate volume was significantly smaller among VA patients both for men with cancer (P = 0.0004) and for men with no evidence of malignancy (P < 0.0001). Overall, the average prostate volume was 38.5 cm3 (median, 32.5 cm3) among men from the VA compared to 46.8 cm3 (median, 39.3 cm3) among men from the University Medical Center. Men from the VA were older (mean +/- SD = 68 +/- 7.3) than men from the University (mean +/- SD = 66 +/- 7.7) (P = 0.004) and there was no significant difference in PSA levels between the two groups of patients (P = 0.11). Intriguingly, the incidence of cancer was significantly lower at the VA (24.5%) compared to the University (35.9%) (P < 0.0001).
Conclusions: The variance in prostate size suggests that there are significant differences between the two patient populations. Proposed factors leading to this discrepancy include differences in socioeconomic factors, environmental factors, and changes in hormonal milieu related to alcohol and tobacco use. These results may have significant implications regarding the interpretation and extrapolation of results from previous studies performed at a single hospital setting.