1. 1Department of Medicine, University of California San Diego, San Diego, California.
2. 2Public Health Sciences, Fred Hutchinson Cancer Center, Seattle, Washington.
3. 3Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland.
4. 4Department of Medicine, Harvard Medical School, Boston, Massachusetts.
5. 5Dana-Farber Cancer Institute, Boston, Massachusetts.
6. 6Cancer Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California.