PSA Testing Interval Reduction In Screening Intervals: Data From The Prostate, Lung, Colorectal And Ovarian Cancer (PLCO) Screening Trial

Reviewer: Roberto Santiago, MD
The Abramson Cancer Center of the University of Pennsylvania
Last Modified: May 19, 2002

Presenter: E. D Crawford
Presenter's Affiliation: Univ of Colorado Health Sciences Ctr, Denver, CO
Type of Session: Plenary


  • Prostate cancer is the most commonly diagnosed malignancy in males and the second leading cause of cancer mortality in males
  • The prostate, lung, colorectal (PLCO) trial is a large, controlled randomized trial evaluating cancer screening versus usual medical care in subjects between the ages of 55 and 74 years that has recruited over 154,000 men and women
  • Among the goals in the male cohort is the evaluation of the pattern of PSA change over 5 years in men with an initial normal PSA to examine alternative screening schedules

Materials and Methods

  • In the screening arm of the trial, the changes in PSA over 5 years was evaluated in 27,863 men who had baseline PSA levels of <4 ng/ml and at least one subsequent PSA exam
  • PSA was yearly assessed by the Hybritech method for 6 years
  • Screening digital rectal examination was performed at the first 4 yearly visits
  • The cumulative probability of converting to PSA >= 4 at years 1 through 5 post baseline was estimated (independent of baseline digital rectal examination)
  • White men constituted 86.1% of the cohort


  • For men with PSA under 1ng/ml at baseline, 98.4% would still have a PSA < 4 ng/ml after 5 subsequent years of annual screening
  • For men with a baseline PSA of 1-2 ng/ml, 97.5% would have a PSA < 4 ng/ml after 2 years of annual screening
  • For men with a baseline PSA of 2-3 ng/ml there is a 34.6% probability of converting to a positive PSA (> 4 ng/ml) after 5 years of annual screening
  • For those with a baseline between 3 and 4 ng/ml the likelihood of having a PSA > 4 ng/ml 5 years after is 83%

Author's Conclusions

  • If a PSA screening strategy that tests every 5 years for men with PSA below 1ng/ml and every 2 years for men with PSA 1-2 ng/ml is implemented a 55% reduction (15.7 million fewer tests) in the number of PSA tests would be achieved
  • This would only result in a small proportion 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

Clinical/Scientific Implications

  • The study did not stratified by age
  • Since controversy exists on whether early identification of an abnormal PSA improves the clinical outcome the impact of this study will depend to a certain degree on the results of prospective randomized studies evaluating prostate cancer mortality among patients undergoing cancer screening versus usual medical care

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