Prostate specific antigen. Its role in the diagnosis and staging of prostate cancer

Abstract

Prostate specific antigen (PSA) is the most valuable clinical tool available for the diagnosis and staging of prostate cancer. Serum PSA can detect twice as many prostate cancers as digital rectal examination can, and nearly two thirds of these detected tumors are organ-confined and potentially curable. While the diagnostic, routine digital rectal examination has no clinically significant effect on the serum PSA concentration, finasteride therapy causes a 50% lowering of the serum PSA value. The new concepts of PSA velocity, free versus complexed PSA, and age-specific reference ranges all appear to improve further the clinic utility of PSA as a detector of early, potentially curable prostate cancers in men who are most likely to benefit from therapeutic intervention. The serum PSA concentration, when combined with the local clinical stage and histologic grade based on the biopsy specimen, is an excellent predictor of pelvic lymph node status. The probability of pelvic lymph node involvement approaches zero for prostate cancer patients who have the following characteristics : local clinical Stage Tla-T2b disease, primary Gleason grade 1 or 2, and a serum PSA level of 17.1 ng/ml or less ; local clinical Stage Tla-T2b disease, primary Gleason grade 3, and a serum PSA level of 8.0 ng/ml or less ; local clinical Stage Tla-T2b disease, primary Gleason grade 4 or 5, and a serum PSA level of 4.2 ng/ml or less ; local clinical Stage T2c disease, primary Gleason grade 1 or 2, and a serum PSA level of 4.1 ng/ml or less ; local clinical Stage T2c disease, primary Gleason grade 3, and a serum PSA level of 2.0 ng/ml or less ; and local clinical Stage T2c disease, primary Gleason grade 4 or 5, and a serum PSA level of 1.0 ng/ml or less. Staging bilateral pelvic lymph node dissection (open or laparoscopic) can be avoided in these select men. Serum PSA is also an excellent predictor of radionuclide bone scan findings. For patients with newly diagnosed, untreated prostate cancer, no skeletal symptoms, and a serum PSA concentration higher than 10 ng/ml, the probability of a positive bone scan approaches zero. For men who present with this clinical scenario, a staging radionuclide bone scan is not necessary. Using serum PSA to eliminate the staging bilateral pelvic lymph node dissection and radionuclide bone scan in select patients can result in significant economic savings to the health care system. Cancer 1995 ; 75 :1795-804.