PSA - A Controversial but Useful Test

With the advent of the PSA (Prostate Specific Antigen) blood test two decades ago, the screening for and detecting of prostate cancer in the United States has been revolutionized.
Introduction

PSA is a protein manufactured in the prostate. There is an association between the PSA level and the likelihood of the man having prostate cancer.
Previously, the only screening test for prostate cancer was a digital rectal exam. That meant a physician inserted his or her gloved finger into the man's rectum to determine if he or she felt any lumps or bumps in the prostate gland. By that point, the cancer was relatively far advanced. Fortunately, PSA blood tests can detect a prostate malignancy at a much earlier stage. This is known as a stage shift.