[1] Stanford Univ, Dept Med, Sch Med, Div Oncol,Stanford Canc Inst, Stanford, CA 94305 USA
[2] Univ Calif Davis, Dept Internal Med, Div Hematol Oncol, Ctr Comprehens Canc, Sacramento, CA 95817 USA
[3] Stanford Univ, Dept Pathol, Sch Med, Stanford Canc Inst, Stanford, CA 94305 USA
[4] Stanford Univ, Dept Hlth & Res Policy, Sch Med, Stanford, CA 94305 USA