Association of interleukin-6 (− 174G>C) promoter polymorphism with risk of squamous cell esophageal cancer and tumor location: An exploratory study

Chronic inflammation plays a role in transformation from normal cell to malignant state. Interleukin-6 (IL-6) regulates inflammation and various physiological processes. IL-6 promoter polymorphism (− 174G>C) is associated with transcription differences in vitro and in vivo. High expression of IL-6 may result in oxidative DNA damage and enhance risk of carcinogenesis. Therefore, we aimed to evaluate association of IL-6 − 174G>C polymorphism with predisposition to esophageal cancer (EC) in 369 subjects (168 patients with EC and 201 controls). We observed significant association of IL-6 − 174C non-carrier genotype with risk of EC, (OR = 2.29; P = 0.001), with squamous cell carcinoma (SCC) histology (OR = 2.26; P = 0.001) and tumor at upper and lower anatomical locations (OR = 5.97; P = 0.009 and OR = 2.34; P = 0.034). Patients having IL-6 − 174C non-carrier genotype were at elevated risk of metastasis (OR = 2.49; P = 0.005). In conclusion, IL-6 − 174G>C gene polymorphism may confer high risk for EC and its clinical characteristics.