Ting-Hui Wu1, James Chih-Hsin Yang2. 1. Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland. 2. Department of Oncology, National Taiwan University College of Medicine, Taipei, Taiwan (Republic of China); Graduate Institute of Oncology, National Taiwan University College of Medicine, Taipei, Republic of China; National Taiwan University Cancer Center, Taipei, Taiwan (Republic of China). Electronic address: chihyang@ntu.edu.tw.