E. D Crawford, David Chia, Gerld L Andriole, Douglas Redding, Edward P Gelmann, John K Gohagan, Paul Pinsky, Richard B Hayes, David L Levin, Richard M Fagerstrom, Barnett S Kramer, Univ of Colorado Health Sciences Ctr, Denver, CO; University of California at Los Angeles, Los Angeles, CA; Washington University School of Medicine, St Louis, MO; Marshfield Clinic and Medical Center, Marshfield, WI; Georgetown University Medical Center, Washington, DC; NIH/NCI, Division of Cancer Prevention, Bethesda, MD; NIH/NCI, Office of Medical Applications of Research, Bethesda, MD.

Purpose: To determine the pattern of prostate specific antigen (PSA) change over 5 years in men with an initial normal PSA. Method: The prostate, lung, colorectal (PLCO) trial is a large, controlled trial that has recruited over 154,000 men and women, ages 55-74, and randomized them to a screening or usual care arm. For men, PSA is assessed (Hybritech method) at each of 6 yearly screening rounds; digital rectal examination (DRE) is carried out at the first four annual exams. We evaluated changes in (total) PSA over 5 years among 27,863 men in the screening arm of the trial who had baseline PSA levels of <4 ng/ml and at least one subsequent PSA exam. A statistical model was used to estimate the cumulative probability of converting to PSA>= 4 at years 1 through 5 post baseline. PSA conversion probabilities were independent of baseline DRE status. Results: The results are illustrated in the table below. Conclusions: This study has found that 98.6% of men with PSA under 1ng/ml at baseline would remain negative (i.e., PSA < 4 ng/ml) after 4 subsequent years of annual PSA testing, and that 98.8% of men with a baseline PSA of 1-2 ng/ml would have a negative PSA test the following year. A strategy of PSA screening every 5 years for men with PSA below 1ng/ml and every 2 years for men with PSA in the 1-2 ng/ml range would produce a 55% reduction in the number of PSA tests, but result in only a small percentage of men missing an earlier potentially positive test. The estimated cost savings of this strategy is on the order of a billion dollars per year.