The design of a study to assess occult-blood screening for colon cancer

It is our experience to date that large numbers of high risk individuals can be induced to use the self-administered Hemoccult test on a periodic basis. The study will determine not only whether a significant reduction in mortality can be effected by such periodic screening for colorectal cancer, but will also attempt to arrive at such parameters as the optimal period for rescreening by estimating mean lead time gained at different rescreening intervals using the methodology of Zelen and Feinleib [10] and Prorok [11, 12]. In addition, screening at two different intervals (Groups I and II) will yield empirical data about the effect of screening frequency on mortality and survivorship. Combining these methodologies may yield new information on optimal screening frequency. Such information could then be used to set up screening programs which would significantly reduce mortality from colorectal cancer on a nation-wide basis.