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Evaluation of association studies, a systematic review and meta-analysis of CYP1A1 polymorphisms, and colorectal cancer risk
  • Lingjun Xu,
  • Xiaofeng He,
  • Xiaoping Wang
Lingjun Xu
Jinan University
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Xiaofeng He
Changzhi Medical College Affiliated Heping Hospital
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Xiaoping Wang
Jinan University
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Abstract

Backgroud: 37 publications and seven previous meta-analyses have been reported to investigate the correlation between CYP1A1 T3801C 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.