1 1 Department of Chronic Disease Epidemiology, Yale School of Public Health, School of Medicine, Yale Cancer Center, Yale University, New Haven, CT 06520-8034, USA ; 2 School of Basic Medical Science and Nursing, Chengdu University, Chengdu 610106, China ; 3 Guizhou Qianxinan People's Hospital, Xingyi 562400, China.