Association of interleukin-6 (-174G/C) polymorphism with the prostate cancer risk: A meta-analysis

The aim of the present study was to determine whether the interleukin-6 (IL-6) (-174 G/C) gene polymorphism correlates with prostate cancer. A meta-analysis based on former studies was conducted and the results suggest that there was no significant association between IL-6 (-174 G/C) polymorphism and the prostate cancer risk. However, a recent study published in January 2014 showed that the GG genotype may be associated with an increased risk of prostate cancer in Caucasian subjects, whereas the CC genotype was associated with an increased risk in the African-American subjects, which was inconsistent with former studies. Databases, including PubMed, Embase, Web of Science, the Cochrane Library, Chinese Biomedical Literature Database and Wanfang database, were searched between January 1994 and March 2014 to determine the eligible IL-6 (-174 G/C) polymorphism studies and the susceptibility of the prostate cancer risk. A total of 11 studies with 10,745 cases and 13,473 controls fulfilled the inclusion criteria subsequent to assessment by two investigators. The pooled odds ratio (OR) with 95% confidence interval (95% CI) was calculated to examine the associations, and subgroup analyses were performed according to the ethnicity. Overall, no significant association was found between the IL-6 (-174 G/C) polymorphism and prostate cancer risk, whereas the subgroup analysis suggested that the association between the IL-6 (-174 G/C) polymorphism and prostate cancer was slightly significant under the homozygote (CC vs. GG: OR, 3.43; 95% CI, 1.01-11.71; P=0.049) and recessive models (CC vs. GG/GC: OR, 3.51; 95% CI, 1.04-11.82; P=0.042) in African-American patients. However, no significant association was found in the Caucasian, Asian or mixed populations under the five genetic models by stratifying studies for ethnicity. In conclusion, the present study suggested that there was no significant association between the IL-6 (-174 G/C) polymorphism and prostate cancer risk in Caucasian and Asian patients, whereas the CC genotype may be associated with an increased risk in the African-American patients.