Background: The Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial (PLCO) is a US National Cancer Institute (NCI)-funded randomized controlled trial designed to evaluate whether certain screening tests reduce mortality from prostate, lung, colorectal, and ovarian cancer. To obtain adequate statistical power, it was necessary to enroll over 150,000 healthy volunteers. Recruitment began in 1993 and ended in 2001.
Purpose: Our goal is to evaluate the success of recruitment methods employed by the 10 PLCO screening centers. We also provide estimates of recruitment yield and cost for our most successful strategy, direct mail.
Methods: Each screening center selected its own methods of recruitment. Methods changed throughout the recruitment period as needed. For this manuscript, representatives from each screening center provided information on methods utilized and their success.
Results: 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. Overall, enrollment yield for direct mail was 1.0%. Individual center enrollment yield ranged from 0.7% to 3.8%. Cost per enrolled participant was $9.64-35.38 for direct mail, excluding personnel costs.
Limitations: Numeric data on recruitment processes were not kept consistently at individual screening centers. Numeric data in this manuscript are based on the experiences of 5 of the 10 centers.
Conclusions: Direct mail, using rosters of names and addresses from profit and not-for-profit (including government) organizations, was the most successful and most often used recruitment method. Other recruitment strategies, such as community outreach and use of mass media, can be an important adjunct to direct mail in recruiting minority populations.