Aims: Several studies evaluated the association between peroxisome proliferators-activated receptor gamma (PPARγ) Pro12Ala (rs1801282), and His477His (rs3856806) polymorphisms and the risk of colorectal cancer (CRC). However, the results were not stable.
Materials and methods: We searched databases containing PubMed and EMBASE. Pooled odds ratios (ORs) and 95% confidence intervals (CIs) were used to assess the strength of the associations.
Results: A significantly decreased CRC risk was found for PPARγ Pro12Ala polymorphism (OR = 0.88, 95% CI 0.83-0.94, P < 0.0001). In the subgroup analysis by race, a significantly decreased risk was found in the Caucasian population (OR = 0.89, 95% CI 0.83-0.95, P = 0.0003) but not in Asian population (OR = 0.76, 95% CI 0.57-1.02, P = 0.07). In the subgroup analysis by CRC location, significantly decreased risks were found in rectal cancer (OR = 0.88, 95% CI 0.77-1.00, P = 0.05) and colon cancer (OR = 0.82, 95% CI 0.73-0.92, P = 0.0008). In addition, a significantly decreased CRC risk was also detected for PPARγ His477His polymorphism (OR = 0.66, 95% CI 0.44-1.00, P = 0.05). In the subgroup analysis by race, a significantly decreased risk was found in the Caucasian population (OR = 0.43, 95% CI 0.26-0.69, P = 0.0006) but not in Asian population (OR = 0.95, 95% CI 0.73-1.25, P = 0.72).
Conclusions: PPARγ Pro12Ala and His477His polymorphisms might be associated with susceptibility of CRC.
Keywords: Colorectal cancer; meta-analysis; peroxisome proliferators-activated receptor gamma; polymorphism.