[1] Univ Calif San Diego, Dept Med, Div Gastroenterol, La Jolla, CA 92093 USA
[2] Univ Calif San Diego, Rebecca & John Moores Comprehens Canc Ctr, La Jolla, CA 92093 USA
[3] VA San Diego Healthcare Syst, San Diego, CA USA
[4] Univ Washington, Sch Med, Dept Med, Seattle, WA 98195 USA
[5] Fred Hutchinson Canc Res Ctr, Seattle, WA 98104 USA
[6] VA Puget Sound Healthcare Syst, Seattle, WA USA