[1] Johns Hopkins Bloomberg Sch Publ Hlth, Dept Epidemiol, Baltimore, MD 21205 USA
[2] Univ N Carolina, Dept Epidemiol, Gillings Sch Global Publ Hlth, Chapel Hill, NC USA
[3] NCI, Infect & Immunoepidemiol Branch, Div Canc Epidemiol & Genet, NIH, Bethesda, MD 20892 USA
[4] Univ N Carolina, Dept Biostat, Gillings Sch Global Publ Hlth, Chapel Hill, NC USA
[5] Brown Univ, Dept Epidemiol, Providence, RI 02912 USA
[6] GlaxoSmithKline, Worldwide Epidemiol, Stockley Pk, Middx, England
[7] McGill Univ, Div Canc Epidemiol, Montreal, PQ, Canada
[8] Univ N Carolina, Lineberger Comprehens Canc Ctr, Chapel Hill, NC 27599 USA