title: The Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial: the prostate cancer screening results in context.
abstract: BACKGROUND
  The Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial (PLCO) was conducted in sites around USA during a period of marked secular changes in the use of prostate specific antigen (PSA) screening for prostate cancer.
  
  
  METHODS
  Trends in prostate cancer incidence, stage at presentation and mortality are useful when interpreting the results from a screening trial that commenced in 1993 and enrolled participants through 2001. The last participants completed active screening in 2006. Incidence and mortality data published to date on PLCO need to be placed into the context of the secular trends. Additional data analyses have been conducted on subsets of the participants and these results can also enhance the interpretation of the trial. Additionally, the accompanying biospecimen repository has served as a rich research resource yielding informative findings.
  
  
  RESULTS
  The PLCO is best viewed as a trial comparing a regimented active annual screening program of PSA screening for six rounds, four of which had accompanying digital rectal examination (DRE) to patterns of screening that were occurring in the population in many academic and community settings across the USA. The epidemiology and molecular genetics of prostate cancer is becoming better understood and analyses of the PLCO resource have contributed. One approach to risk assessment utilizing genetic markers from selected members of the PLCO prostate cancer cohort has been developed. A modeling effort with CISNET-ERSPC-PLCO is underway to compare and contrast findings such as effects of different PSA thresholds and screening intervals.
  
  
  CONCLUSIONS
  The information emerging from PLCO is useful to inform the debate around prostate cancer screening. An understanding of the biologic differences underpinning indolent and aggressive prostate cancer will better guide the future development of screening and treatment strategies.
authors: Early Detection Research Group, Division of Cancer Prevention, National Cancer Institute, Bethesda, MD 20852, USA. bergc@mail.nih.gov
authors: Christine D
authors: CD
authors: Berg