[1] Fred Hutchinson Canc Res Ctr, Div Publ Hlth Sci, Seattle, WA 98105 USA
[2] British Columbia Canc Agcy, Vancouver, BC V5Z 4E6, Canada
[3] Univ Washington, Dept Epidemiol, Seattle, WA 98195 USA
[4] Harborview Med Ctr, Int Med Clin, Seattle, WA USA
[5] Univ Washington, Dept Med, Seattle, WA USA
[6] Univ Washington, Dept Hlth Serv, Seattle, WA USA