Interleukin-18 (IL-18) is a novel immunoregulatory cytokine that was known previously as interferon-γ–inducing factor. IL-18 levels can be used as a serum indicator for monitoring the clinical course of patients with hematologic malignancies and gastric carcinoma. Nitric oxide (NO) is a pleiotropic molecule that participates in the multistep processing of carcinogenesis.
In the current study, we measured serum IL-18 and nitrate and nitrite levels in 38 metastatic and 26 nonmetastatic breast carcinoma patients and 16 healthy control subjects. Serum nitrate and nitrite levels were measured as an index of NO generation.
The levels of serum IL-18 and nitrate and nitrite were increased significantly in breast carcinoma patients compared with control subjects (P < 0.001). Serum IL-18 levels were significantly higher in the metastatic patients compared with the nonmetastatic patients (P < 0.001). There was no difference in serum nitrate and nitrite levels between metastatic and nonmetastatic patients (P > 0.05). Patients with bone metastasis have higher serum IL-18 levels and lower serum nitrate and nitrite levels compared with patients with liver, lung, and local metastasis (P < 0.001). There was no correlation among serum IL-18, nitrate and nitrite, CA 15-3, and carcinoemybryonic antigen levels (P > 0.05).
These findings suggest that serum IL-18 and nitrate and nitrite levels may be useful markers in monitoring metastatic breast carcinoma pateints. IL-18 and NO activities in breast carcinoma patients with bone metastasis may be more valuable in the follow-up of these patients. Cancer 2002;95:663–7. © 2002 American Cancer Society.