Comparison of prostate size in university and Veterans Affairs Health Care System patients with negative prostate biopsies

Objectives. Many important prostate studies take place at Veterans Affairs hospitals. We have examined whether the patient population at these institutions is comparable to the population presenting for prostate evaluation at university hospitals. Methods. We included all patients presenting for transrectal ultrasound (TRUS) and biopsy in whom systematic biopsies failed to reveal prostate cancer at both Stanford University Medical Center (90 patients) and the Palo Alto Veterans Affairs Health Care System (103 patients) from August 1, 1995 to July 31, 1996. Identical techniques and equipment for TRUS examination and prostate size determination were used at both institutions. Results. There was no significant difference in the age or prostate-specific antigen (PSA) levels of the patients at the two institutions. The mean prostatic volume of the Stanford University patients was 71 cm³ (median 63 cm³), whereas the mean prostatic volume of patients at the Palo Alto Veterans Affairs hospital was 52 cm³ (median 43 cm³), a highly statistically significant difference (P = 0.0009). Conclusions. The smaller size of the prostate glands in Veterans Affairs patients may be the result of differences in referral base, socioeconomic factors, or environmental factors. These data may have significance for trials conducted only on the prostates of men who are seen at Veterans Affairs hospitals.