Subgroup analysis of the association between GSTM1 null genotype and lung cancer risk.

¤: Geographical locations of China were divided into 7 parts: Northeast of China (Jilin province, Liaoning province, Heilongjiang province), North China (Beijing city, Tianjin city, Heber province, Shanxi Province (Taiyuan), Inner Mongolia), East China (Shanghai city, Anhui province, Jiangxi province, Jiangsu province, Zhejiang province, Fujian province, Shandong province, Taiwan), Central China (Henan province, Hubei province, Hunan province), South China (Guangdong province, Hainan province, Guangxi Zhuang Autonomous Region, Hongkong), Southwest of China (Chongqing City, Guizhou province, Sichuan Province, Yunnan Province, Tibet), Northwest of China (Shanxi province (xi'an), Gansu province, Ningxia Hui Autonomous Region, Xinjiang Uyghur autonomous region).M: model of meta-analysis; R: random-effects model; F: fixed-effects model.PH: p value of heterogeneity test. PE:p value of Egger's test.POR: PP = 0.000 and P less than 0.001. @: p values could not be calculated.: the publication bias was detected in this group. ¶: Newcastle-Ottawa Scale (NOS).: test materials of case or control was from the normal lung tissues, BALF cells, buccal cells or lung cancer tissue.:the study of Wang YS et al was not included because of the unavailable data.