Serum interleukin-6 levels in colorectal cancer patients—a summary of published results

Introduction It is now clear that inflammation and cancer initiation and progression are linked. Interleukin-6 (IL-6) is a pleiotropic inflammatory cytokine with described cancer stimulatory and also cancer inhibitory properties. The study’s aim was to assess the potential of circulating IL-6 as a prognostic indicator in colorectal cancer. Materials and methods A literature search was conducted using PubMed, restricted to articles published in English language. We compared published results in regard to differences in IL-6 levels between healthy controls and colon cancer patients (seven published results), between patients with increasing tumor stages (eight published results), between patients with differences in tumor size (four published results), and between patients with and without liver (three published results) or lung metastasis (one published result). Furthermore, we reviewed the literature in regard to the possible correlation of IL-6 levels with survival time (five published results) and correlation of IL-6 levels and lymph node involvement (three published results). Results Concerning colon tumors, results are consistent. Colon cancer patients reveal higher serum IL-6 levels than healthy controls. Furthermore, higher IL-6 levels are associated with increasing tumor stages and tumor size, with metastasis and decreased survival. Conclusion Therefore, circulating IL-6 might be prognostic indicator in colorectal cancer.