Prospective analysis of expression of circulating levels of matrix metalloproteinase-9 (MMP-9) in the serum of patients with primary central nervous system lymphoma (PCNSL)

1532 Background: Matrix metalloproteinases have been associated with angiogenesis, tumor infiltration and metastases formation in systemic lymphoma. Disease status in PCNSL is determined by brain MRI; however it may be inconclusive and non-invasive tests to evaluate disease status would be useful. This study was designed to determine whether circulating levels of MMP-9 could be related to disease status in PCNSL. Methods: Circulating levels of MMP-9 were determined by ELISA and correlated with disease status assessed by MRI in a prospective longitudinal study. The disease status was classified as no evidence of disease (CR) versus active disease (AD). Results: We enrolled 18 PCNSL patients and obtained 93 blood samples (median 6 per patient, range 1–10) from August 2002 to December 2005. When in CR (12 patients, 59 samples), the mean MMP-9 level was 205.5 ± 19.1 ng/ml (median 162.3 ng/ml, range: 35.9–649.1 ng/ml). MMP-9 levels were significantly higher in AD (16 patients, 34 samples), with a mean MMP-9 of...