NCI's Largest Cancer Screening Trial Now Enrolling Men and Women Ages 55 to 74

Moving into the final recruitment phase, the researchers of theProstate, Lung, Colorectal, and Ovarian Cancer Screening Trial(PLCO) are seeking 75,000 more men and women ages 55 to 74 tohelp them determine whether medical tests to detect some of themost common cancers reduce the number of deaths from these diseases.This largest-ever US cancer screening trial will include a totalof 148,000 men and women in 10 cities: Denver, Colorado; Washington,DC; Honolulu, Hawaii; Detroit, Michigan; Minneapolis, Minnesota;St Louis, Missouri; Brooklyn, New York; Pittsburgh, Pennsylvania;Salt Lake City, Utah; and Marshfield, Wisconsin.

Together, prostate, lung, colorectal, and ovarian cancers accountfor nearly half of all cancers diagnosed and half of all cancerdeaths in the United States. Late in 1995, the age range for PLCOtrial participants was expanded from ages 60 to 74 to ages 55to 74. "Almost 80% of cancers occur in people who are age55 and older," said John Gohagan, phd, Chief of NCI's EarlyDetection Branch and project officer for the study. "By loweringthe age for participation, we are including more people who arealready at risk." The investigation began in November 1993.

The tests being studied may detect these cancers before symptomsdevelop, but whether treatments at this stage will reduce thechance of dying from the diseases is unknown. Some cancer screeningtests very clearly reduce the number of deaths from the disease-forexample, Pap tests reduce deaths from cervical cancer. But manyother medical tests are being routinely used to screen healthypeople for cancer when there is no definitive evidence that theyreduce the number of deaths from the disease.

PLCO trial participants are being randomized to one of two groups:Half the participants undergo the tests being studied (interventiongroup), and half receive whatever usual health care their doctorsprovide (control group). Both groups will answer yearly questionnairesabout their health.

Tests Under Study

"Whether the participants receive their usual care from theirphysicians or receive cancer screening tests at the PLCO centers,they are playing an important role," Dr. Gohagan said. Bycomparing the numbers of cancers diagnosed, side effects of treatingthe cancers, and the numbers of cancer deaths in the interventiongroup with those in the control group, the researchers will beable to determine if the cancer screening tests had an overallbenefit. The following tests are being studied:

• For prostate cancer, men have a digital rectal examinationof the prostate and a blood test for prostate-specific antigen.
• For lung cancer, both men and women receive a regular chestx-ray.
• For colorectal cancer, men and women are screened with flexiblesigmoidoscopy.
• For ovarian cancer, women have a physical examination of theovaries, a blood test for the tumor marker CA125, and a transvaginalultrasound.

The intervention group has these tests done at their initial visitand during the third year of participation. Participants in boththe intervention and control groups are contacted yearly for atleast 10 years from the time they enter the study in order forthe researchers to monitor their health.

Men and women interested in participating in the PLCO trial shouldcontact the center nearest them. Locations of the centers canbe found by calling NCI's Cancer Information Service at 1-800-4-CANCER(1-800-422-6237). Information about the PLCO trial can also befound on the World Wide Web at http://www.dcpc.nci.nih.gov/PLCO.