Study characteristics
A flow diagram was shown in Fig. 1. Overall, 37 publications were selected to analyze the CYP1A1 T3801C and A2455G polymorphisms with CRC risk. The current and published meta-analyses involving studies were shown in supplemental Table 1. The eligible studies characteristics were listed in supplemental Table 2. Of these, 27 studies (involving 9,672 cases and 12,689 controls; eight studies on Asians, fourteen on Caucasians, and five on mixed populations; ten studies on Asia; nine on Europe; five on North America, one on South America, and one on Ocean) for CYP1A1 T3801C polymorphism and 24 studies (involving 8,933 cases and 11,692 controls; seven studies on Asians, twelve on Caucasians, and five on mixed populations; seven studies on Asia; nine on Europe; five on North America, two on South America, and one on Ocean) for CYP1A1 A2455G polymorphism were performed in the current pooled analysis. Supplementary Tables 3-5 shows the study characteristics by location of CRC, gender, and site of CRC, respectively.