Survivin and angiotensin-converting enzyme polymorphisms with risk of colorectal cancer: a systematic review and meta-analysis

Background: Colorectal cancer (CRC) is the most common cause of cancer death worldwide. Numerous studies have identified the roles of survivin -31 G/C and angiotensin-converting enzyme insertion/deletion (ACE I/D) polymorphisms in CRC risk; however, the results remain inconclusive. This study was to investigate associations between these two polymorphisms and CRC susceptibility. Methods: A comprehensive literature search was conducted to collect relevant case-control studies published between 2000 and 2014. The extracted data were statistically analyzed, and the odds ratios (ORs) with 95% confidence intervals (CIs) were employed to estimate the strength of association. Results: A total of 11 studies were included in the meta-analysis. For survivin G/C polymorphism, six articles reported 1,840 cases and 1,804 controls. Overall, we found the frequency of C allele is higher in CRC cases than that in the healthy controls (57.2% vs. 48.0%), and C allele significantly increased the risk of CRC compared to G allele in allele model (OR = 1.46, 95% CI = 1.33-1.60, P < 0.00001). This association was also found in other genetic models (P < 0.00001). Stratified analysis by ethnicity showed significant association in each genetic model among the Asian population. For ACE I/D polymorphism, five studies included 758 cases and 6,755 controls. No significant association was found in any genetic models. Conclusions: Our results showed that survivin -31 G/C polymorphism might contribute to risk of CRC, especially in the Asian populations. However, the ACE I/D polymorphism is not a genetic factor concerning the risk for CRC. More studies with larger sample sizes are required in the future.