[1] Washington Univ, Sch Med, Alvin J Siteman Canc Ctr, St Louis, MO 63110 USA
[2] Washington Univ, Sch Med, Div Med Oncol, 660 South Euclid,Campus Box 8056, St Louis, MO 63110 USA
[3] Washington Univ, Sch Med, Dept Radiat Oncol, St Louis, MO 63110 USA
[4] Washington Univ, Sch Med, Dept Otolaryngol, St Louis, MO 63110 USA
[5] Washington Univ, Sch Med, Div Biostat, St Louis, MO 63110 USA