The Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial, sponsored by the National Cancer Institute (NCI), reached a significant milestone last month with the enrollment of its final participant.

"We are pleased to announce that nearly 155,000 generous men and women are investing their time and effort participating in this important clinical trial," said John Gohagan, Ph.D., chief of the Early Detection Research Group, Division of Cancer Prevention, and the project officer for PLCO.

Although the recruitment phase is complete, PLCO will continue to collect and analyze essential health data from participants to determine if certain cancer screening practices reduce the number of deaths from prostate, lung, colorectal, and ovarian cancer. These cancers together account for 48 percent of all cancers diagnosed and 49 percent of all cancer deaths in the United States.

"The Data Safety and Monitoring Board includes clinical experts in PLCO cancers as well as expert biomedical statisticians. Besides monitoring the safety of the trial, they assure that scientifically valid results are published as soon as they are available," said Gohagan. Initial results may become available in the next five years, after health data is collected and analyzed from the participants. However, it will be several years before researchers know if the screening protocols reduce mortality.

For prostate cancer, PLCO centers screen men with a digital rectal exam and a blood test for prostate-specific antigen (PSA). For lung cancer, centers screen men and women with a chest X-ray. For colorectal cancer, men and women are screened with flexible sigmoidoscopy. For ovarian cancer, women are screened with both a blood test for the tumor marker known as CA-125, and transvaginal ultrasound.

PLCO is a randomized controlled cancer screening trial. The participants were randomized by computer lottery, with their informed consent, to either a screening or a usual care group. Participants in the usual care group continue to receive the routine care by their personal health care providers. Participants in the screening group received all gender-appropriate PLCO screening tests at their initial visit and again every year for the next three years. PSA and CA-125 screening is also offered in the fourth and fifth years. The sigmoidoscopy exam is offered only twice—at the initial visit and at either the third or fifth annual visit, depending when the participant enrolled in PLCO. With the completion of enrollment, researchers will continue to screen and follow participants in both groups for up to 14 years from the time they enrolled.

"A fundamental mission of the NCI is reducing cancer death rates. PLCO is assessing the impact of screening with specific tests on deaths from four major cancers," said Gohagan.

The ten PLCO Screening Centers nationwide include: the University of Colorado, Denver, Colo.; Georgetown University Medical Center, Washington, DC; Pacific Health Research Institute, Honolulu, Hawaii; Henry Ford Health System, Detroit, Mich.; University of Minnesota, Minneapolis, Minn.; Washington University, St. Louis, Mo.; University of Pittsburgh, Pittsburgh, Pa.; University of Utah, Salt Lake City, Utah; Marshfield Medical Research and Education Foundation, Marshfield, Wis.; and University of Alabama at Birmingham.

For more information regarding other screening trials and additional information about cancer, please visit NCI's Web site at http://www.cancer.gov.

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