[1] Natl Univ Singapore, Yong Loo Lin Sch Med, Natl Univ Hosp, Dept Pathol, Singapore 117595, Singapore
[2] Natl Univ Singapore, Oncol Res Inst, Singapore 117595, Singapore
[3] Natl Univ Singapore, Yong Loo Lin Sch Med, Natl Univ Hosp, Dept Med, Singapore 117595, Singapore
[4] Univ Arizona, Arizona Hlth Sci Ctr, Dept Med, Infect Dis Sect, Tucson, AZ USA
[5] Univ Calif Irvine, Chao Family Comprehens Canc Ctr, Irvine, CA USA