Abstract
Background: 37 publications and seven previous meta-analyses
have been reported to investigate the correlation between CYP1A1T3801C and A2455G polymorphisms with CRC risk. However, the results were
contradictory. Original studies were not involved in previously
published meta-analyses. Moreover, their meta-analyses did not evaluate
positive results to identify multiple comparisons.
Objectives: We performed an updated meta-analysis and
systematically evaluated the published meta-analyses on the association
between CYP1A1 T3801C and A2455G polymorphism with CRC
susceptibility.
Results: CYP1A1 T3801C polymorphism was not associated
with CRC risk when all the selected studies were merged. However,
subgroup analyses according to ethnicity, geographic region, location of
CRC, gender and smoking, showed a significant association in rectal
cancer and females. However, after BFDP correction, false significant
associations were observed in rectal cancer (CC vs. TT: BFDP = 0.998; CC
vs. (TT + TC): BFDP = 0.998; C vs. T: BFDP = 0.999) and females (TC vs.
TT: BFDP = 0.999). A significantly increased CRC risk was yielded in
overall analysis, Caucasians, Europe countries populations, and males
for CYP1A1 A2455G polymorphism. After BFDP correction,
associations still be significant only in Europe countries populations
(AG vs. AA: BFDP = 0.680; (AG + GG) vs. AA: BFDP = 0.475; G vs. A: BFDP
= 0.126). However, when we further performed a sensitivity analysis and
BFDP test, false significant associations were observed in all analyses
(BFDP > 0.8).
Conclusions: In summary, this study suggests that these
positive findings may result from false-positive results, rather than
from true associations or biological factors.
Keywords: CYP1A1 , polymorphism, colorectal cancer,
meta-analysis