Matrix Metalloproteinase-9 (MMP-9) Expression in Non-Small Cell Lung Carcinoma and Its Association with Clinicopathologic Factors

Background & Objective: Matrix metalloproteinases-9 (MMP-9) is one of the most important enzymes to breakdown extracellular matrix which plays a major role in tumor invasion and metastasis. This study aimed to determine tumor MMP-9 expression in non-small-cell lung carcinoma (NSCLC) and whether it is associated with histopathologic factors and has prognostic value to affect overall survival (OS).

Methods: The specimens of 92 patients with NSCLC diagnosis were included. Tumor sections were stained by immunohistochemistry method. Using scores for the percentage of cells positively stained and the intensity of staining, MMP-9 expression total score was classified as low-score (scores of 0 to 2), moderate-score (scores of 3 to 5), or high-score (scores of 6 or 7). OS was defined as the time interval since the diagnosis of NSCLC to the status at the last follow-up (dead or alive). The follow up period was up to 70 months.

Results: About 74% of undifferentiated specimens (grade III tumors) showed high scores for MMP-9 expression which was significantly higher than moderately differentiated tumors (25% had high scores for MMP-9 expression) and well differentiated ones which did not have high scores (<0.001). A total of 74 patients (80.4%) died during the follow-up period. Of this, 36% had high scores for MMP-9 expression. In contrast, none of the patients who were alive at the last follow-up had high scores for MMP-9 expression (<0.001). Median OS was significantly lower in high score group (6 months) compared to moderate score (9 months) and high score group (15 months) (<0.001).

Conclusion: MMP-9 expression may serve as a significant prognostic factor for mortality and overall survival in NSCLC. Undifferentiated tumors significantly express higher MMP-9 immunohistochemically.