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A Critical Look at Prevention: Colorectal Cancer Screening


This preventive medicine teaching case, part of the Cases in Population-Oriented Prevention series, discusses the concepts of:

  • Diagnostic test evaluation
  • Prevention
  • Screening using the example of colorectal cancer screening

Features of the case include a health policy exercise concerning community screening programs and an exercise in clinical prevention decision-making.


  • Calculate the characteristics of diagnostic tests: sensitivity, specificity and positive and negative predictive values
  • Evaluate screening tests in terms of their validity, results and generalizability
  • Employ the concepts of primary and secondary prevention as they relate to common clinical preventive services
  • Describe the appropriate conditions for screening in terms of characteristics of the disease, the patient and the screening test
  • Describe the appropriate study design to evaluate the effectiveness of a screening program and discuss the common biases encountered in screening program research
  • Evaluate locally obtained survey data about screening rates and attitudes and devise a community response to increase colorectal cancer screening