Although prostate specific antigen velocity was proposed to increase the specificity of prostate specific antigen-based screening, there are little published data on the effect of differential prostate growth on prostate specific antigen velocity. If a patient presents with rising prostate specific antigen over a year or more, it would be useful to know whether such a change in prostate specific antigen could be explained by prostate growth. Thus, we investigated the relationship between changes in prostate size and prostate specific antigen changes in a large cohort of men without prostate cancer. We identified 242 men without prostate cancer from the Baltimore Longitudinal Study of Aging who had 2 or greater serial pelvic magnetic resonance imaging studies and contemporaneous prostate specific antigen measurements. In this population we used the t test, correlation coefficients, and regression analysis to examine the relationship between prostate specific antigen changes and prostate volume changes, as assessed by magnetic resonance imaging. The mean age was 55 years. During 4.2 years of median followup, the median rate of volume change was 0.6 cc per year (range -9.9 to 11.8), and the median prostate specific antigen change was 0.03 ng/ml per year. There was no correlation between prostate specific antigen changes and prostate growth, as measured in cc per year (r = -0.01, p = 0.9) or the percent change per year (r = 0.07, p = 0.3). On multivariate analysis, there was no significant relationship between changes in prostate volume and prostate specific antigen changes.
Our data suggest that volume increases alone do not cause a high prostate specific antigen velocity. Despite growth rates as high as 10 cc per year, prostate specific antigen velocity was less than 0.1 ng/ml per year in most men without prostate cancer. Thus, differential rates of prostatic growth should not confound the use of prostate specific antigen velocity for prostate cancer detection and prognostication.
Does prostate growth confound prostate specific antigen velocity?