[1] Erasmus Univ, Med Ctr, Dept Publ Hlth, Rotterdam, Netherlands
[2] Univ Penn, Perelman Sch Med, Dept Family Med & Community Hlth, Philadelphia, PA 19104 USA
[3] Southern Calif Kaiser Permanente Grp, San Diego, CA USA
[4] Univ South Carolina, Jones Phys Sci Ctr, Dept Biol Sci, Columbia, SC USA
[5] Univ South Carolina, Jones Phys Sci Ctr, Ctr Colon Canc Res, Columbia, SC USA
[6] Mem Sloan Kettering Canc Ctr, Dept Epidemiol & Biostat, New York, NY 10021 USA