CSF-1 and Ang-2 serum levels — prognostic and diagnostic partners in non-small cell lung cancer

BACKGROUND: Lung cancer is the most incident and lethal form of cancer, with late diagnosis as a major determinant of its bad prognosis. Immunotherapies targeting immune checkpoints improve survival, but positive results encompass only 30%–40% of the patients, possibly due to alternative pathways to immunosuppression, including tumour-associated macrophages (TAM). Colony stimulating factor-1 (CSF-1) is implicated in TAM differentiation and recruitment to tumours and in tumour angiogenesis, through a special setting of Tie-2-expressing macrophages, which respond to angiopoietin-2 (Ang-2). We evaluated the role of serum levels of CSF-1 in non-small cell lung cancer (NSCLC) prognosis and whether these could serve as biomarkers for NSCLC detection, along with Ang-2. PARTICIPANTS AND METHODS: We prospectively studied an unselected cohort of 145 patients with NSCLC and a group of 30 control individuals. Serum levels of Ang-2 and CSF-1 were measured by ELISA prior to treatment. RESULTS: Serum levels of CSF-1 and Ang-2 are positively correlated (p<0.000001). Individuals with high serum levels of CSF-1 have a 17-fold risk for NSCLC presence and patients with combined High Ang-2/CSF-1 serum levels present a 5-fold increased risk of having NSCLC. High Ang-2/CSF-1 phenotype is also associated with worst prognosis in NSCLC. CONCLUSIONS: Combined expression of CSF-1 and Ang-2 seems to contribute to worst prognosis in NSCLC and it is worthy to understand the basis of this unexplored partnership. Moreover, we think CSF-1 could be included as a biomarker in NSCLC screening protocols that can improve the positive predictive value of the current screening modalities, increase overall cost effectiveness and potentially improve lung cancer survival.