Peroxisome proliferator-activated receptor-γ (PPARγ) Pro12Ala polymorphism and colorectal cancer (CRC) risk

The association between the peroxisome proliferator-activated receptor-γ (PPARγ) Pro12Ala polymorphism and colorectal cancer (CRC) risk was inconclusive. We conducted a meta-analysis to evaluate the association between PPARγ Pro12Ala polymorphism and CRC risk. We searched Pubmed, EMBASE, and China National Knowledge Infrastructure databases. Data were extracted and pooled odds ratios (OR) with 95% confidence intervals (CI) were calculated. A total of 17 case-control studies with 12635 and 15803 controls were included in this meta-analysis. Overall, PPARγ Pro12Ala polymorphism was associated with CRC risk (OR = 0.84, 95% CI 0.75-0.94, P = 0.003, I(2) = 35%). In the subgroup analysis by ethnicity, a significant association was found among Caucasians (OR = 0.85, 95% CI 0.75-0.96, P = 0.007, I(2) = 38%) but not among Asians (OR = 0.76, 95% CI 0.51-1.12, P = 0.17, I(2) = 28%). In the subgroup analysis by CRC site, a significant association was found among colon cancer (OR = 0.81, 95% CI 0.66-0.98, P = 0.03, I(2) = 16%) but not among rectal cancer (OR = 0.83, 95% CI 0.57-1.21, P = 0.34, I(2) = 63%). The sensitivity analysis did not influence the result by omitting low-quality studies (OR = 0.76, 95% CI 0.63-0.93, P = 0.006, I(2) = 51%). In conclusion, this meta-analysis suggested that PPARγ Pro12Ala polymorphism was significant associated with CRC risk.