[1] Med Coll Wisconsin, Dept Radiat Oncol, Milwaukee, WI USA
[2] Ohio State Univ, Wexner Sch Med, Ctr Biostat, Secondary Data Core, Columbus, OH USA
[3] Ohio State Univ, Coll Med, Columbus, OH USA
[4] Univ Toronto, Princess Margaret Canc Ctr, Dept Radiat Oncol, Toronto, ON, Canada
[5] Ohio State Univ, Wexner Sch Med, James Canc Ctr, Dept Radiat Oncol, Columbus, OH USA
[6] Dartmouth Geisel Sch Med, Dept Radiat Oncol, Hanover, NH USA
[7] Ohio State Univ, Wexner Sch Med, Dept Gastroenterol, Div Hepatol, Columbus, OH USA
[8] Ohio State Univ, Wexner Sch Med, James Canc Ctr, Dept Radiat Oncol, 460 W 10th Ave, Columbus, OH 43210 USA