Interleukin-6-174G>C gene promoter polymorphism and prognosis in patients with cancer

Interleukin-6 (IL-6) is known to be involved in the pathogenesis of cancer progression. IL-6-174G>C polymorphism has shown several results in association studies. In this study, we evaluated the association the IL-6-174G>C polymorphism and overall survival (OS) of cancer using 17 eligible studies with 4,304 patients. Our meta-analysis indicated that IL-6-174G>C polymorphism is not associated with OS when assessed using 3 genotype comparison including GG/(GC+CC), CC/(GC+GG) and CC/GG. Interestingly, compared to GG carrier, patients with IL-6-174GC genotype showed a decreased hazard of poor OS (hazard ratio = 0.81, 95% confidence interval: 0.68-0.96, P = 0.018; I2 = 34.5%, Phet = 0.107). However, for GG/(GC+CC) genotype comparison, this SNP is affect patients' OS obviously in bladder cancer, ovarian and peritoneal cancer, neuroblastoma, gastric cancer and osteosarcoma, though pooled results showing negative association because adverse and protective effect on different type of cancer balance each other. These results suggest IL-6-174G>C polymorphism might play a role in modulating OS in different type of cancer and might contribute to individual treatment in the future.