Matrix metalloproteinase-9 (MMP-9) elevated in serum but not in bronchial lavage fluid in patients with lung cancer

Aims and background: Matrix metalloproteinase (MMP) family member MMP-9 degrades type IV collagen, which is one of the main constituents of the basement membrane. MMP-9 is closely associated with the invasive and metastatic potential of most types of lung cancer. In this study we investigated the levels of MMP-9 in serum and bronchial lavage fluid from lung cancer patients and compared them with the levels in patients with nonmalignant lung disease. We also attempted to clarify the possible relationship between serum and bronchial lavage fluid MMP-9 levels and histopathology, staging and metastasis of lung cancer. Study design: The study group consisted of 34 patients with lung cancer. The control group comprised 21 patients with nonmalignant lung disease. MMP-9 levels in serum and bronchial lavage fluid were evaluated by ELISA. Results: MMP-9 levels in serum samples from the group with malignant disease were significantly higher than those from the control group (P < 0.05). Bronchial lavage MMP-9 levels did not differ significantly between the two groups (P > 0.05). Serum MMP-9 levels were two-fold higher than those in bronchial lavage, but there was no correlation between bronchial lavage and serum levels in both groups (r = 0.18, P > 0.05). In the group with malignant disease, MMP-9 levels in serum and bronchial lavage fluid did not show any relationship with histopathological type and tumor stage. There was a statistically significant correlation between serum MMP-9 levels and local tumor stage in smoking non-small cell lung cancer (NSCLC) patients (r = 0.33, P < 0.05). Karnofsky scores of lung cancer patients were inversely correlated with MMP-9 levels of serum (r = -0.39, P < 0.05) but not of bronchial lavage fluid. Conclusion: From our data it can be concluded that MMP-9 levels of serum but not of bronchial lavage fluid can be helpful in differentiating between malignant and benign lung diseases, and are related to the local stage in NSCLC patients and general clinical status of lung cancer patients.