A German cohort study has shown that a low baseline prostate-specific antigen (PSA) level in middle age is associated with a reduced long-term risk of prostate cancer. The study included 1,482 men with serum PSA levels less than 1.00 ng/ml. A single PSA test in middle age can thus identify the long-term risk of this disease. Low PSA values indicate a lower risk of developing prostate cancer in the future.