The association of interleukin-6 gene polymorphism and risk of colorectal cancer in Chinese patients

Background: Clinical and experimental data have strongly revealed a vital role of interleukin-6 (IL-6) in the development of both sporadic and colitis-associated colorectal cancer (CRC) development. The aim of our study is to discover the association between CRC risk in Chinese people and one variant (rs1800795) in IL-6 gene which was reported to significantly associate with CRC risk in Caucasian population. Methods: We included 186 CRC patients and 200 age-and gender-matched control individuals from the Wuxi Traditional Chinese Hospital. We used one customized assay of IL6-174G/C from Applied Biosystems to genotype one IL-6 gene polymorphisms (rs1800795) through real time-RCR method. All statistical analyses were conducted with SPSS 17.0 by Student's t-test, chi(2) test, Fisher's exact test or logistic regression. Results: Finally, our studies showed the C allele would significant increase the CRC risk in female [odds ratio (OR): 1.741, 95% confidence interval (CI): 1.037, 2.924, P value: 0.035] and non-smokers (OR: 2.425, 95% CI: 1.626, 3.617, P value: <0.001). And the significant associations exited in the genotype distributions of rs1800795 polymorphism and CRC risk in non-smokers (P value: <0.001), drinkers (P value: 0.026) and the samples of non-high fat diet (P value: 0.006). Our studies showed significant positive relations between rs1800795 polymorphism and CRC risk in tumor node metastasis (TNM) stage I (OR: 4.841, 95% CI: 4.220, 5.554, P value: <0.001) and TNM stage II (OR: 1.138, 95% CI: 1.034, 1.252, P value: 0.008). The further study of CRC subtypes indicated that rs1800795 polymorphism indicated a better prognosis in rectum patients. Conclusions: This study is the first report of IL-6 gene polymorphisms among CRC patients from China. The results indicated that screening the rs1800795 polymorphism in specific groups would be a promising method to predict the risk of CRC. However, more large size of population needed to verify these results, and further studies needed to be conducted to explore its potential mechanism.