Elevated serum pro-MMP2 levels in patients with stage IV thymoma

Abstract. Purpose: There is increasing evidence that matrix metalloproteinases (MMPs) play important roles in tumor invasion and metastasis. Using a one-step sandwich enzyme immunoassay, we investigated whether serum pro-MMP2 levels could be predictors of the development and extension of thymoma. Methods: The subjects of this study were 33 patients with thymoma and 26 patients with nonmalignant thoracic disease. Results: Serum pro-MMP2 levels were elevated in patients with stage IV thymoma (938.6 ± 80.2 ng/ml) compared with those in the controls (P= 0.03). Patients with stage IVb thymoma had significantly higher serum pro-MMP2 levels than patients with other stages, being 1088.7 ± 440 ng/ml in stage IVb, 686.0 ± 74.0 ng/ml in stage I (P= 0.01), 685.8 ± 48.6 ng/ml in stage II (P= 0.01), and 691.7 ± 74.0 ng/ml in stage III (P= 0.02). Serum pro-MMP2 levels were elevated in patients with polygonal cell type thymoma compared with those with mixed cell type thymoma, being 823.1 ± 55.5 ng/ml vs 613.6 ± 59.9 ng/ml, respectively (P= 0.04). Using the reference limit of 850 ng/ml (mean ± 2SD) set from analyses in the control group, all patients who had pro-MMP2 levels below the cutoff level survived. On the other hand, four of nine patients who had an elevated pro-MMP2 level died from recurrence. Conclusion: Serum pro-MMP2 levels may serve as a marker that could be used as an indicator of distant metastases in thymoma. Elevated pro-MMP2 levels may be correlated with poor survival. Received: June 29, 2001 / Accepted: November 20, 2001