The role of PSA and percent free PSA for staging and prognosis prediction in clinically localized prostate cancer.

Prostate-specific antigen (PSA) is the most important tumor marker for early detection, staging, and monitoring of men with prostatic cancer today. However, its sensitivity and specificity are not sufficient to use it as a single tool for screening for men with clinically localized prostate cancer. Recently, assays have become available that selectively detect several of the various molecular forms of PSA, especially the unbound or free PSA. Several studies have shown the clinical usefulness of percent free PSA (free PSA/total PSA) for the early detection of men with clinically localized prostate cancer. However, the use of percent free PSA for staging of prostate cancer remains controversial. Based on the case scenario presented, the value of total PSA and percent free PSA for the staging of men with clinically localized prostate cancer is reviewed.