Lack of Association Between Interleukin-8-251 T>A Polymorphism and Colorectal Cancer Risk: a Meta-analysis based on 3,019 Cases and 3,984 Controls

PURPOSE: The results of recent published studies focusing on IL-8 polymorphism in colorectal cancer susceptibility have often been inconsistent. We therefore carried out a meta-analysis based on independent studies to assess the association. METHODS: Nine case-control studies with 7,003 individuals (3,019 cases and 3,984 controls) were included in this meta-analysis through searching the databases of PubMed, Excerpta Medica Database (EMBASE), and Chinese Biomedical Literature Database (CBM; Chinese) (up to Aug 1st, 2012). The odds ratio (OR) and 95% confidence interval (95%CI) were used to assess the strength of the association. Meta-analysis was conducted in a fixed/random effect model. RESULTS: No obvious associations were found for all genetic models when all studies were pooled into the meta-analysis (for A vs. T: OR = 1.084, 95% CI = 0.971- 1.209, P = 0.019; for TA vs. TT: OR = 1.18, 95% CI = 0.943-1.475, P = 0.001; for AA vs. TT: OR = 1.155, 95% CI = 0.916-1.456, P = 0.014; for AA+TA vs. TT: OR = 1.170, 95% CI =0.953-1.437, P = 0.001; for AA vs. TT+TA: OR = 1.044, 95% CI = 0.886-1.230, P = 0.097). In the subgroup analyses by ethnicity (Caucasian) and source of controls (population based), also no significant associations were found for all genetic models. CONCLUSIONS: Result suggests that the IL-8-251T>A polymorphism is not associated with colorectal cancer risk. Because of the limitations of this meta-analysis, this finding demands further investigation.