Non‐Hodgkin lymphoma (NHL) represents a heterogeneous group of tumors that vary with regard to their biologic aggressiveness and clinical course. In in vitro studies, matrix metalloproteinase 9 (MMP9) was reportedly expressed by human NHL cells and elevated levels of MMP9 have been observed in a subset of patients with high‐grade NHL.

The expression of MMP2 and MMP9 was evaluated in 158 patients with NHL and the relation between the expression of these proteins and clinicopathologic factors was analyzed. All but 1 patient had received radiation therapy and 92 patients also were treated with intensive combination chemotherapy.

Nearly all the patients with extranodal natural killer NK/T‐cell lymphoma nasal type and anaplastic large cell lymphoma, T‐cell/null cell type expressed MMP9. In contrast, only a small fraction of the patients with mucosa‐associated lymphoid tissue (MALT) lymphomas and follicular lymphomas expressed MMP9. Approximately 50% of the diffuse large B‐cell lymphoma (DLBCL) cases expressed MMP9. The expression of MMP2 was noted in some of the patients with DLBCL and nasal NK/T‐cell lymphoma. The overall survival rates of patients who expressed MMP9 were significantly lower than that of those who did not. Such a correlation was not demonstrated in MMP2 expression. When MMP9 expression was analyzed in DLBLC patients, the overall survival rates of patients who expressed MMP9 were significantly lower than those who did not express MMP9. Chemotherapy was associated with better overall survival in DLBCL patients who expressed MMP9. Overall survival rates of T‐cell/NK‐cell lymphoma patients who expressed MMP9 appeared to be lower than that in those who did not express MMP9. However, chemotherapy was not found to improve overall survival in patients who expressed MMP9.

MMP9 expression was observed in patients with aggressive NHL and was characterized by poor overall survival. Cancer 2004;100:356–65.© 2003 American Cancer Society.