Cytokine serum levels in soft tissue sarcoma patients: Correlations with clinico‐pathological features and prognosis

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Abstract
We investigated the correlations between serum levels of selected proinflammatory, hematopoietic and angiogenic cytokines and soluble cytokine receptors with the clinico-pathological features and prognosis in soft tissue sarcoma patients. Serum levels of 9 cytokines (TNFα, IL-1ra, IL-6, IL-8, IL-10, M-CSF, G-CSF, VEGF, bFGF) and 4 free cytokine receptors (sIL-2Rα, sIL-6R, TNFRI, TNFRII) were measured by means of an enzyme-linked immunoadsorbent assay kit in 156 soft tissue sarcoma patients before the treatment and in 50 healthy controls. Serum levels of 10 cytokines and cytokine receptors were also assayed during patients' follow-up after the treatment. Significantly elevated pretreatment serum levels of 11/13 cytokines and cytokine receptors were found in sarcoma patients, as compared to healthy controls. In 40.4% of patients 6 or more cytokines and cytokine receptors (most frequently: TNF RI, IL-6, IL-8) were elevated in parallel. Serum levels of IL-6, sIL-2R, VEGF, M-CSF and TNF RI correlated significantly with tumor size and serum levels of IL-8 and IL-6 were significantly higher in patients with Grade 2/3 vs. Grade 1 tumors. We did not observe any significant differences in cytokine serum levels between patients with primary and recurrent tumors and patients with and without distant metastases. Using univariate analysis, overall survival (OS) in all patients was affected by tumor size (10 cm), tumor grade (G1 vs. G2/3), presence of metastases, pretreatment serum levels of 8 cytokines (IL-6, IL-8, IL-10, sIL-2R, TNF RI, TNF RII, M-CSF, VEGF) and the number of cytokines increased (0–1 vs. 2–5 vs. ≤6). Elevated serum levels of IL-6, IL-8, IL-10 and sIL-2Rα, high tumor grade and larger tumor size strongly correlated with shorter disease-free survival (DFS). Multivariate analysis identified G2/3 tumor grade (p = 0.001), the presence of metastases (p = 0.004), elevated IL-6 serum level (p = 0.02), elevated IL-8 serum level (p = 0.048) and the number of cytokine serum levels above upper cut-off values (p = 0.01) as the independent prognostic factors related to OS, and G2/3 tumor grade (p = 0.005) and increased IL-6 serum level (p = 0.035) as independent prognostic factors related to DFS. In a group of patients without metastases (M0) higher tumor grade, elevated serum level of IL-6 and TNF RII, and the number of elevated cytokine serum levels correlated independently with poor survival. We found a significant decrease of several cytokine serum levels in patients after treatment (IL-1ra, IL-6, IL-8, IL-10, TNF RII, M-CSF) [p < 0.05]. Persistently elevated serum level of IL-6 after the treatment has also shown negative prognostic significance for OS (univariate analysis). Serum levels of some proinflammatory, hematopoietic and angiogenic cytokines and cytokine receptors are elevated, frequently in parallel, in a large percentage of soft tissue sarcoma patients. Significant correlations of serum cytokine levels with tumor size and grade suggest that some of these cytokines may be directly or indirectly involved in the progression of soft tissue sarcomas. Serum assays of IL-6, IL-8 and TNF RII before or after the treatment may be useful in establishing soft tissue sarcoma patients prognosis.