[Genetic polymorphism in cytochrome P450 2E1, salted food and colorectal cancer susceptibility: a case-control study].
OBJECTIVE
To investigate PstI allelic variants of cytochrome P450 2E1 (CYP2E1), the interaction effect on salted food and their role in risk for colorectal cancer.


METHODS
The genotypes of CYP2E1 PstI restriction fragment length polymorphism were analyzed in 126 colorectal cancer cases and 343 normal controls. The unconditional logistic regression was applied to estimate the OR and its 95% CI.


RESULTS
The CYP2E1 C1/C1, C1/C2 and C2/C2 genotypes were found respectively in 61.8%, 35.8% and 2.4% of normal control, similar to rectal cancer cases. The percentage of PstI variant genotype (54.9%: 52.9% C1/C2 and 2.0% C2/C2) in colon cancer cases was significantly higher than that in controls (adjusted OR1.979, 95% CI 1.090 approximately 3.595). Stratified analysis suggested an interaction between CYP2E1 C2 allele and salted food. The odds ratio (OR) for the CYP2E1 variant genotype, salted food eaten weekly or biweekly and eaten every day or every other day were 1.935, 2.122 and 2.315, respectively, while those of salted food combined with variant genotype eaten weekly or biweekly and eaten every day or every other day were 2.272 and 3.127. The role in risk for rectal cancer was different from that for colon cancer. Whatever the CYP2E1 genotype is, the risk for rectal cancer came to marked when salted food was consumed weekly or biweekly (OR = 2.646 and 2.297, respectively). However, none but the combined effect of variant genotype and salted food eaten every day or every other day had the notably risk for colon cancer and the odds ratio suddenly increased to 4.262 (95% CI 1.395 approximately 13.017), 1.69-fold higher than that of wild genotype (P = 0.072).


CONCLUSIONS
The CYP2E1 C2 allele is a susceptibility factor for colorectal cancer, especially for colon cancer, and there is an apparent gene-environment interaction between the susceptible genotype and salted food.
Yu
Wei-ping
WP
Department of Epidemiology and Bio-statistics, School of Public Health, Zhejiang University, Hangzhou 310031, China.
Chen
Kun
K
Ma
Xin-yuan
XY
Yao
Kai-yan
KY
Jiang
Qin-ting
QT
Zou
Yan
Y
Zhou
Hai-guang
HG
D000483:Alleles; D016022:Case-Control Studies; D002681:China / Q000453:epidemiology; D015179:Colorectal Neoplasms / Q000453:epidemiology / Q000235:genetics*; D019392:Cytochrome P-450 CYP2E1 / Q000235:genetics*; D005260:Female; D005519:Food Preservation; D020022:Genetic Predisposition to Disease; D005838:Genotype; D006801:Humans; D008297:Male; D017720:Molecular Epidemiology; D012150:Polymorphism, Restriction Fragment Length; D012307:Risk Factors; D012492:Salts
D012492:Salts; D019392:Cytochrome P-450 CYP2E1