In 1993, the Prostate, Lung, Colorectal, and Ovarian trial was launched The trial was designed to determine whether certain screening tests reduce the number of deaths from these cancers. The trial began recruiting men and women, ages 55-74.

In the United States between 1993 and 2001, ten screening centers enrolled 154,934 study participants. Based on participant self-report, an estimated 95% of individuals were recruited by direct mail.