Elevated serum pro-MMP2 levels in patients with stage IV thymoma.
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. The subjects of this study were 33 patients with thymoma and 26 patients with nonmalignant thoracic disease. Serum pro-MMP2 levels were elevated in patients with stage IV thymoma (938.6+/-80.2ng/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+/-440ng/ml in stage IVb, 686.0+/-74.0ng/ml in stage I (P = 0.01), 685.8+/-48.6ng/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+/-55.5ng/ml vs 613.6+/-59.9ng/ml, respectively (P = 0.04). Using the reference limit of 850ng/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. 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.