Lower Serum Matrix Metalloproteinase‑9 in Metastatic Patients with Esophageal Squamous Cell Carcinoma After Concurrent Radiotherapy Was Significant for Prognosis

AIM: This study was designed to investigate the relationships of serum matrix metalloproteinase 9 (MMP-9) level and treatment response in esophageal squamous cell carcinoma (ESCC) patients treated with chemotherapy or concurrent radiotherapy. METHODS: Blood samples from ESCC patients after chemotherapy or concurrent radiotherapy were collected at four different intervals. Serum MMP-9 was determined via Luminex assay in 134 patients with chemotherapy, 73 patients with concurrent radiotherapy, and 183 healthy controls. RESULTS: Serum MMP-9 level was significantly higher in patients with ESCC than in healthy controls (P <0.001). Compared with the pre-treatment, a lower level of serum MMP-9 was maintained at four cycles of treatment in ESCC patients with concurrent radiotherapy (P < 0.001). Serum MMP-9 level was obviously lower in ESCC patients with metastasis after concurrent radiotherapy than after chemotherapy (P < 0.05). Patients with higher MMP-9 level (≥820.693 ng/mL) had a shorter mean survival time by 42 months versus lower MMP-9 level (<820.693 ng/mL) after chemotherapy or concurrent radiotherapy (P < 0.001). CONCLUSION: Serum MMP-9 is a potential prognostic biomarker for treatment response to chemotherapy or concurrent radiotherapy in terms of overall survival (OS) in ESCC patients.