• Division of Cancer Control and Population Sciences, National Cancer Institute, Bethesda, MD, USA. marcusp@mail.nih.gov

OBJECTIVES: To report participant recruitment experiences in a large, US randomized controlled trial (RCT) of lung cancer screening, with the aim of providing information that may be of use to researchers who wish to conduct similar future studies.

SETTING: The National Lung Screening Trial (NLST), an RCT that demonstrated a 20% lung cancer mortality reduction with low dose helical computed tomography screening, relative to single-view chest radiograph screening. Thirty-three US medical centres recruited 53,454 participants from August 2002 through April 2004.

METHODS: After recruitment was completed, centre co-ordinators were asked to complete a questionnaire addressing the extent to which specific methods were used and, for each specific method, numbers enrolled and total cost of the effort. Cost per enrollee was calculated. Co-ordinators also were asked to report lessons learned.

RESULTS: Twenty-two centres returned questionnaires. Use of recruitment method varied by centre. Among centres reporting number enrolled by method, about 19,000 participants were enrolled with direct mail, about 4200 with mass media, and about 1000 with community outreach. Cost per enrollee varied across centres but medians were (US) $101 (direct mail), $79 (mass media), and $4 (community outreach). Co-ordinators reported that it was important to know where to find persons likely to be eligible and interested, and how best to approach them.

CONCLUSIONS: Most NLST participants were recruited through direct mail, although median cost per participant was highest for that method.