Collection of buccal cell genomic DNA occurred during May 1999 and June 2006 using a mouthwash kit.
Eligible individuals had completed a baseline questionnaire after enrollment into the cohort, had a known current address, were alive at the date of the request for a buccal cell sample, and had been enrolled in CCSS at a site with institutional review board approval for collection and storage of buccal cell DNA.
Participants were mailed a specimen collection kit that included a cover letter describing the study, consent form, instruction sheet, 45 ml. bottle of mouthwash, specimen collection container, return mail labels, and postage. Subjects were instructed to rinse their mouths with the mouthwash and return the used mouthwash to the Molecular Genetic Laboratory in Cincinnati, Ohio, in the sterile container.