Inclusion and exclusion criteria
The inclusion criteria were as follows: (1) case–control or cohort
studies, (2) explored the correlation between the CYP1A1 T3801C
and A2455G polymorphisms and CRC risk, and (3) gave the genotype data of
cases and controls or the odds ratio (OR) with their 95% confidence
intervals (CI). Exclusion criteria were as follows: (1) review articles,
(2) case reports, (3) editorials, (4) systematic review and
meta-analyses, (5) other SNP, (6) other disease, (7) animal studies, and
(8) duplicate data.