Figure 12. Charts showing relationship of prostate volume to serum PSA levels (right) and PCA3 score (left). While PSA is directly related to prostate volume, the PCA3 score appears to have no relationship to prostate volume. Thus, prostate volume, one of the primary factors influencing serum PSA levels, is not a confound of the PCA3 score. Improved cancer specificity is a major advantage of PCA3 testing. From L.S. Marks, et al, 2006 AUA Meeting, Atlanta, GA.