[1] Abramson Family Canc Res Inst, Dept Med, Philadelphia, PA USA
[2] Univ Penn, Sch Med, Dept Biostat & Epidemiol, Philadelphia, PA 19104 USA
[3] Univ Penn, Sch Med, Ctr Canc, Philadelphia, PA 19104 USA
[4] Georgetown Univ, Med Ctr, Vincent T Lombardi Canc Res Ctr, Washington, DC 20007 USA