Local Concentrations of CC-Chemokine-Ligand 18 Correlate with Tumor Size in Non-small Cell Lung Cancer and Are Elevated in Lymph Node-positive Disease

Abstract

Background: The tumor microenvironment plays a critical role in tumor growth and spreading. Tumor-associated macrophages (TAM) make up a large proportion of the tumor mass and are one of the main producers of CC-chemokine ligand 18 (CCL18), which is believed to carry out important functions in the immunological interactions that promote tumor progression.

Materials and methods: Cytokines/chemokines were measured in bronchoalveolar lavage (BAL) from the tumor site and serum before and after resection in patients with proven non-small cell lung cancer (NSCLC).

Results: CCL18 concentrations in BAL positively correlated with the radiologically determined tumor volume (r=0.72, p=0.0003) in NSCLC. In addition, tumors with lymph-node metastasis exhibited significantly higher CCL18 concentrations in BAL (p=0.049) than those without. Serum CCL18 concentrations did not differ significantly before and after tumor resection.

Conclusion: The increased release of CCL18 with greater tumor size is most likely due to the accompanied growth of leukocyte infiltrate. With previous findings taken into account, this could be one factor contributing to tumor invasiveness and particularly lymphatic spread in patients with larger tumors.

Keywords: CCL18; TAM; lymphatic spread; tumor associated macrophages; tumor microenvironment.