The PSA test measures the body’s level of a protein called prostate-specific antigen to detect the presence of prostate cancer in men. The PSA test is considered twice as reliable as a rectal exam in the diagnosis of early prostate cancer.
The PSA test is not infallible; a man’s PSA level tends to rise when the prostate becomes enlarged, but the enlargement may or may not be due to cancer. Patients will sometimes have a false-positive reading, or will have cancer that remains undetected after a PSA test. Therefore, doctors often recommend a rectal exam to accompany the PSA test. Although this test is not foolproof, doctors administer the PSA test because it is cheap, easy to give, and has improved detection of early prostate cancer dramatically.
