Cyclooxygenase 2 polymorphism and colorectal cancer: -765G>C variant modifies risk associated with smoking and body mass index.
OBJECTIVE
To explore whether cyclooxygenase 2 (COX-2) -765G>C polymorphism is associated with susceptibility of colorectal cancer (CRC) and to evaluate the risk of colorectal cancer in relation to environmental exposures and polymorphism.


METHODS
We conducted a case-control study of 137 patients with colorectal cancer and 199 cancer-free controls in northeast China. Multivariate logistic regression analysis was performed to calculate the adjusted odds ratio (OR) and 95% confidence interval (95% CI).


RESULTS
The -765G>C polymorphism was not independently associated with CRC risk. However, risk associated with the polymorphism differed by smoking and body mass index (BMI). Smoking and BMI associated risks were stronger among those with -765GG genotype, showing that smokers had a 2.682-fold greater risk of CRC than nonsmokers (51/43 vs 68/126, P = 0.006). Compared to those with a normal body mass index (BMI 18.5-22.9), those with overweight (BMI 23-24.9) had a 3.909-fold higher risk of CRC (OR = 3.909, 95% CI = 2.081-7.344; P < 0.001), while those with obesity (BMI > 25) had a 2.031- fold higher risk of CRC (OR = 1.107, 95% CI = 1.107-3.726; P = 0.022).


CONCLUSIONS
Although COX-2 -765G>C polymorphism is not associated with an increased risk of CRC, -765GG genotype appears to be related to an increased risk in the presence of smoking and higher BMI.
Xing
Li-Li
LL
Department of Surgical Oncology and General Surgery, The First Affiliated Hospital of China Medical University, Shenyang 110001, Liaoning Province, China.
Wang
Zhen-Ning
ZN
Jiang
Li
L
Zhang
Yong
Y
Xu
Ying-Ying
YY
Li
Juan
J
Luo
Yang
Y
Zhang
Xue
X
D015992:Body Mass Index; D016022:Case-Control Studies; D002681:China; D015179:Colorectal Neoplasms / Q000201:enzymology / Q000235:genetics*; D051546:Cyclooxygenase 2 / Q000235:genetics*; D005260:Female; D015971:Gene Expression Regulation, Enzymologic; D015972:Gene Expression Regulation, Neoplastic; D020022:Genetic Predisposition to Disease; D006801:Humans; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D011110:Polymorphism, Genetic; D011401:Promoter Regions, Genetic; D018570:Risk Assessment; D012307:Risk Factors; D012907:Smoking / Q000009:adverse effects*
D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human