The value of the prostate-specific antigen (PSA) test as a diagnostic tool for prostate cancer has declined following changes in medical practice, according to a new study. Study author Dr. Douglas S. Scherr said that the PSA test is still very predictive in men with an abnormal digital rectal examination, while for men with a normal digital rectal examination, the test’s predictive accuracy has declined. For the latter category of men, doctors are opting for biopsies and are using improved biopsy techniques.