Figure 1

The distribution of study sites in China. The 11 higher level centers included Beijing (2 centers), Tianjin, Shenyang (Liaoning Province), Xi'an (Shaaxi Province), Changsha (Hunan Province), Chongqing, Shenzhen (Guangdong Province), Shanghai, Nanjing (Jiangsu Province) and Fuzhou (Fujian Province). The seven lower level centers included Dashiqiao County (Liaoning Province), Hetian County (Xinjiang Autonomous Region), Xinmi Prefecture (county-level, Henan Province), Panyu/Conghua County (Guangdong Province), Tonggu County (Jiangxi Province), Yangcheng County and Changzhi Prefecture (Shanxi Province). Data related to the less-developed centre in Southwest China were not available. Most of the study hospitals have had well established collaboration with CICAMS on a number of prior studies associated with HPV and cervical cancer.