Key Programs

Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial

The Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial, or PLCO, is a large-scale clinical trial to determine whether certain cancer screening tests reduce deaths from prostate, lung, colorectal and ovarian cancer. The underlying rationale for the trial is that screening for cancer may enable doctors to discover and treat the disease earlier. Numerous epidemiologic and ancillary studies are included to answer related crucial questions, as noted in the About PLCO pages.

Together, these four cancers are estimated to account for about 42 percent of all diagnosed cancers in the United States and 46 percent of cancer deaths in 2007.

Sponsored and run by the National Cancer Institute's Division of Cancer Prevention, in collaboration with the Division of Cancer Epidemiology and Genetics, the PLCO trial is taking place at 10 Screening Centers across the country.

Between 1992, when the trial opened, and 2001, when enrollment ended, 155,000 women and men between the ages of 55 and 74 joined PLCO. At entry, participants were divided by chance into one of two study groups. One group received routine health care from their health providers. The other received a series of exams to screen for prostate, lung, colorectal, and ovarian cancers. Screening of participants ended ahead of schedule in late 2006. Follow-up will continue for up to 10 more years to determine the benefits or harms of screening, with new data noted in the News Updates pages and the PLCO Publications pages (through the Program Administrative Resource site) as they are published.

The Etiology and Early Marker Studies (EEMS)is a component of the PLCO Trial. By collecting biologic materials and risk factor information from trial participants before the diagnosis of disease, PLCO EEMS adds substantial value to the trial, providing a resource for cancer research, focused, in particular, on cancer etiology and early markers.