Characteristics of the studies related with the effects of GSTs genetic polymorphisms and HCC risk.

ALL: HCC cases were confirmed by pathologic diagnosis; PARTIAL: part of HCC cases were confirmed by pathologic diagnosis; NA: relative data were not available in original studies;*Articles published in English;̂Articles published in Chinese.§McGlynn et al. did not show genotype frequency of cases and controls, but presented OR with 95% CI;Southeast regions in China mainland include Hebei, Shanghai, Jiangsu, Zhejiang, Anhui, Jiangxi, and Guangxi. Central regions in China mainland include Hunan and Henan.