[1] Univ Calif San Francisco, Dept Med, Div Hematol Oncol, San Francisco, CA 94143 USA
[2] Stanford Univ, Dept Med, Sch Med, Div Oncol, Stanford, CA 94305 USA
[3] VA Palo Alto Healthcare Syst, Div Oncol, Palo Alto, CA USA
[4] Stanford Univ, Ctr Hlth Policy Primary Care Outcomes Res, Dept Med, Sch Med, Stanford, CA 94305 USA