Repeating an abnormal prostate-specific antigen (PSA) level: how relevant is a decrease in PSA?

To examine the practice of repeating an abnormal prostate-specific antigen (PSA) level before proceeding to prostate biopsy, we assessed the pattern of PSA change following an initially raised (>or=4.0 ng ml(-1)) PSA, and the relationship of this to prostate cancer diagnosis. In 7052 men, 71.2% with initially raised PSA had a reduction in PSA, with values <4.0 ng ml(-1) in 37.8%. A total of 43.0% of men with prostate cancer showed a PSA decrease below their baseline level. Short-term decreases in PSA may occur in men with prostate cancer, including high-grade cancer, and so should not influence the decision to proceed to prostate biopsy.