Because healthy tissues, fluid-filled cysts, and cancer can produce different echoes, the test is potentially useful in detecting ovarian diseases. Doctors expect to enroll 148,000 men and women between the ages of 60 and 74 in the trial at 10 medical centers across the country. These volunteers must not have any of the cancers for which they might be screened in the study, although a diagnosis of other cancers may not exclude their participation. Men participating in the Prostate Cancer Prevention Trial, where 18,000 men will take either the drug finasteride or a placebo to assess the drug's effect on the prevention of prostate cancer, are not eligible to participate in the PLCO Trial. Women participating in the Breast Cancer Prevention Trial, where 16,000 women at increased risk of breast cancer are taking either tamoxifen or a placebo to assess the drug's ability to prevent the disease, are not eligible to participate in the PLCO Trial.
Cancer occurs more often as people grow older.
More than 60 percent of all cancers occur in the 12 percent of the population who are over age 65. Because risk for the disease is so great in older persons, they are the most appropriate population to study. The benefits of the tests being studied are unknown, and they may not provide any advantage to the participants. By comparing the number of cancers diagnosed and the number of cancer deaths in both the intervention and control groups, the researchers will be able to determine the potential benefit of the tests under study. This information is part of the comparison between the groups and will be used to learn more about risks for these diseases.