Interleukin-6 Blood Level Is Associated With Circulating Carcinoembryonic Antigen and Prognosis in Patients With Colorectal Cancer

Abstarct Background: Interleukin-6 (IL-6) is an important proinflammatory cytokine that has multiple effects on stimulating inflammation and cell growth. Experimental data suggest that carcinoembryonic antigen (CEA) induces the systemic production of IL-6 and that IL-6 may stimulate tumor cell growth at metastatic sites. We tested the hypothesis that blood concentrations of IL-6 are associated with the amount of circulating CEA and with prognosis in patients with colorectal cancer.Methods: CEA and IL-6 concentrations were measured by using enzyme immunoassay in preoperative serum samples from 208 patients with stages I through IV colorectal cancer.Results: Linear regression analysis showed a significant association between serum values of CEA and IL-6 (r = .544; R² = .296; P < .001). Patients with stage III and stage IV disease had a significantly higher IL-6 serum concentration than those with stage I and stage II disease. In patients with stages I through III, 5-year survival was 83% in cases with concentrations of IL-6 at 10 pg/ml or less (n = 94) and 56% in cases with IL-6 concentrations of more than 10 pg/ml (n = 54; P = .001; median follow-up time, 46 months). By using multivariate analysis, an IL-6 concentration of more than 10 pg/ml was an independent prognostic factor of survival (relative risk = 1.820; P = .020).Conclusions: In patients with colorectal cancer, blood concentration of IL-6 is associated with high circulating CEA and advanced stage. Furthermore, an IL-6 concentration of more than 10 pg/ml is an independent negative prognostic marker of survival.Presented at the 52nd Annual Meeting of Society of Surgical Oncology, Orlando, Florida, March 4–7, 1999.