[1] Univ Maryland, Sch Med, Dept Radiat Oncol, Baltimore, MD 21201 USA
[2] Univ Copenhagen, Dept Oncol, Rigshosp, Dept Oncol, Copenhagen, Denmark
[3] Univ Maryland, Med Ctr, Dept Radiat Oncol, Baltimore, MD 21201 USA
[4] Univ Maryland, Sch Med, Greenebaum Comprehens Canc Ctr, Baltimore, MD 21201 USA
[5] Univ Maryland, Sch Med, Dept Epidemiol & Publ Hlth, Baltimore, MD 21201 USA