Association between glutathione S -transferases M1 and T1 gene polymorphisms and prostate cancer risk: a systematic review and meta-analysis

Genetic polymorphisms in glutathione S -transferases M1 (GSTM1) and T1 (GSTT1) genes have been widely reported and considered to have a significant effect on prostate cancer (PCa) risk, but the results are inconsistent. To evaluate the impact of the GSTM1 and GSTT1 polymorphism on PCa risk, we conducted a comprehensive meta-analysis based on 18 eligible studies. A total of 18 studies, including 7,119 subjects for GSTM1 and 6,454 subjects for GSTT1 between 1999 and 2012 were identified through researching MEDLINE, PubMed, Web of Science, EMBASE, Chinese National Knowledge Infrastructure database, and Chinese Biomedical Literature database. A meta-analysis was performed to obtain summary-estimated odd ratios and 95 % confidence intervals of GSTM1 and GSTT1 polymorphisms for PCa, with attention to study quality and publication bias. Overall, there is a significant association between GSTM1 (odds ratio (OR) = 1.407, 95 % confidence intervals (95 % CI) = 1.147–1.727, I 2 = 73.2 %, P = 0.001) genotypes and PCa susceptibility. Significant associations were also observed in subgroups of Caucasian populations (OR = 1.262, 95 % CI = 1.055–1.511, I 2 = 48.7 %, P = 0.011) and Asian populations (OR = 1.776, 95 % CI = 1.134–2.781, I 2 = 83.4 %, P = 0.012). However, no significant association was found (OR = 1.776, 95 % CI = 1.134–2.781, P = 0.243) in African-American populations when stratified by ethnicity. While, there was no significant association seen between GSTT1 (OR = 1.003, 95 % CI = 0.823–1.298, I 2 = 68.8 %, P = 0.778) genotypes and PCa risk. However, no significant associations were observed in subgroups of Caucasian populations (OR = 1.086, 95 % CI = 0.801–1.471, I 2 = 72.1 %, P = 0.597) and Asian populations (OR = 0.961, 95 % CI = 0.644–1.434, I 2 = 73.0 %, P = 0.846), and similar result was found among African-American populations (OR = 0.802, 95 % CI = 0.194–3.321, P = 0.761) when stratified by ethnicity. Our results suggest that the GSTM1 gene polymorphism contributes to PCa susceptibility, while GSTT1 gene polymorphism is not associated with PCa in our study.