PGP and colorectal carcinoma: Osswald et al. reported there was interaction between the combination of several ABCB1 polymorphisms including 3435C>T polymorphism and the status of smoking and age in relation to CRC risk.14 Furthermore, several studies did not found association between ABCB1 3435C>T polymorphism and CRC risk.15-18 In addition, Indicibus et al. reported there was no association between the expression of P-gp and ABCB1 3435C>T polymorphism.18 The pooled result of this meta-analysis indicated that the homozygous TT genotype of ABCB1 3435C>T polymorphism probably not affect CRC risk.