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World J Gastroenterol. Mar 21, 2008; 14(11): 1785-1789
Published online Mar 21, 2008. doi: 10.3748/wjg.14.1785
Cyclooxygenase 2 polymorphism and colorectal cancer: -765G>C variant modifies risk associated with smoking and body mass index
Li-Li Xing, Zhen-Ning Wang, Li Jiang, Yong Zhang, Ying-Ying Xu, Juan Li, Yang Luo, Xue Zhang
Li-Li Xing, Zhen-Ning Wang, Yong Zhang, Ying-Ying Xu, Juan Li, Department of Surgical Oncology and General Surgery, the First Affiliated Hospital of China Medical University, Shenyang 110001, Liaoning Province, China
Li Jiang, Yang Luo, Xue Zhang, Department of Medical Genomics of China Medical University, Shenyang 110001, Liaoning Province, China
Author contributions: Xing LL and Wang ZN designed the research; Xing LL ,Zhang Y, Xu YY and Li J conducted the research; Jiang L, Luo Y and Zhang X provided analytic tools; Xing LL, Wang ZN analyzed data and wrote the paper.
Correspondence to: Dr. Zhen-Ning Wang, Department of Surgical Oncology and General Surgery, The First Affiliated Hospital of China Medical University, Shenyang 110001, Liaoning Province, China. josieon826@yahoo.com.cn
Telephone: +86-24-83283556
Received: May 10, 2007
Revised: July 20, 2008
Published online: March 21, 2008
Abstract

AIM: 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).

CONCLUSION: 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.

Keywords: Colorectal cancer; Cyclooxygenase 2; Polymorphism; Smoking; Body mass index