Exhaled Matrix Metalloproteinase-9 in Lung Cancer

Background: Matrix metalloproteinase-9 (MMP-9) has been recognized in several types of tumor development and progression, including lung cancer, for its role in the degradation and remodeling of lung tissue. Furthermore, increased MMP-9 has been commonly described in the serum and airways of non-small cell lung cancer (NSCLC) patients. Objective: The aim of this study was to investigate, for the first time, MMP-9 in the exhaled breath condensate (EBC) of NSCLC patients. Participants: We enrolled 40 NSCLC patients and 40 controls affected by transudative pleural effusion. Measurements: MMP-9 concentrations were measured in the EBC, whole blood (WB), and pleural effusion (PE) of all the subjects under study using enzyme immunoassay (EIA) kits. Results: MMP-9 levels were found to be significantly higher in EBC, WB, and PE of NSCLC patients compared with controls. A positive correlation was observed between MMP-9 in EBC, cigarettes smoked, and stage of cancer. Conclusion: Exhaled MMP-9 was elevated in NSCLC patients, especially during tumor progression, and could represent a suitable noninvasive marker in the diagnosis and monitoring of lung cancer.