How is PSA used to detect prostate cancer?
The PSA test is used in two distinctly different ways with respect to detecting prostate cancer. It can be used in men who are not known to have the disease (screening or diagnostic test) and those who are known to have the disease (tumor marker or monitoring test). As a screening or diagnostic test, an abnormal result will usually require additional testing. Levels above 4 ng/mL but less than 10 ng/mL are suspicious. However, most men who have this level of abnormality will actually not have prostate cancer. As levels increase above 10 ng/mL, the probability increases dramatically. As a tumor marker or monitoring test, an abnormal result indicates recurrence of prostate cancer following initial therapy. For example, if the prostate gland is surgically removed (prostatectomy), and all of the cancer is contained within the gland, then the PSA should drop to zero. If on subsequent testing the PSA test is positive and shows increasing levels, then not all of the cancer was successfully re
