IGF-I CA19 repeat polymorphisms and cancer risk: a meta-analysis.

IGF-I CA repeat polymorphisms, especially the allele containing CA19 repeats, have been reported to be associated with the risk for various types of cancers. However, the results still remain controversial and ambiguous. This meta-analysis was performed to evaluate the association between IGF-I CA19 repeat polymorphisms and the risk of cancer. Total 18 studies with IGF-I CA19 repeat genotyping on 9,873 patients and 15,607 controls were analyzed. We used random-effects model with a pooled OR of 0.69 (95% CI = 0.60-0.79) for the recessive genetic model, 0.97 (95% CI = 0.86-1.10) for the dominant genetic model, 0.99 (95% CI = 0.86-1.14) for the homozygote comparison and 1.06 (95% CI = 0.91-1.23) for the heterozygote comparison. In the subgroup analysis of recessive model, OR (95% CI) was 0.65 (0.52-0.80) in breast cancer, 0.68 (0.53-0.86) in prostate cancer, and 0.71 (0.52-0.96) in Caucasian. In conclusion, IGF-1 CA19 repeat polymorphisms are unlikely to be a major determinant of susceptibility to cancer. However, the subgroup analysis of recessive model indicates that IGF-I CA19 repeat polymorphisms may reduce the risk of certain types of cancer or in a specific population.