Assessment of connective tissue metabolism in patients with head and neck malignancies treated with radiotherapy

Introduction: Despite the use of highly specialized irradiation techniques in the treatment of head and neck tumors, it is still impossible to selectively destroy cancer cells without damaging normal structures, including connective tissue cells. Aim: The aim of the study was to analyze the concentration of degradation markers such as collagen type I (carboxyterminal telopeptide of type I collagen; ICTP) and elastin (elastin-derived peptides; EDPs) as well as selected metalloproteinases (MMP-1, MMP-2, MMP-9) in patients with head and neck malignancies undergoing radiotherapy. Material and methods: The test group consisted of 56 men, who underwent radical or palliative radiotherapy. The concentrations of ICTP, EDPs, MMP-1, MMP-2, MMP-9 were determined in three blood samples collected from patients prior to radiotherapy, immediately after its completion and 3 months after the therapy. Results: Both radical and palliative radiotherapy contribute to a significant increase in the concentration of EDPs. At the time of healing of post-irradiation lesions, the level of EDPs was reduced in both groups. The ICTP concentration was not affected by radiotherapy. No significant differences were observed in the concentration of MMP-1 and MMP-2 before and after radiotherapy. Radical radiotherapy caused a statistically significant late reduction in the concentration of MMP-9. The lowest concentrations of MMP-1, MMP-2, MMP-9 in the serum of patients qualified for palliative radiotherapy were recorded in a samples collected three months post-irradiation. Conclusions: The degradation markers of key extracellular matrix structural proteins may be helpful tools in the objective assessment of radiation-induced injuries to the connective tissue.