Relationship of classification to biologic behavior of non-Hodgkin's lymphomas

The classification of non-Hodgkin's lymphomas (NHLs) is an important factor in treatment. Most clinical protocols divide these tumors into two broad categories--indolent, or low-grade, and aggressive, or high-grade. Patients with low-grade NHLs usually have a relatively long survival, with or without the use of aggressive therapy. Although the tumors can be controlled with conventional chemotherapeutic approaches, they are rarely cured. Patients with high-grade tumors usually die within 1 to 2 years without therapy. However, with aggressive treatment, many patients can be cured if complete remissions can be sustained for at least 2 years. Several types of NHLs represent distinct clinicopathologic entities--lymphoblastic lymphoma, adult T cell leukemia/lymphoma, true histiocytic lymphoma, Burkitt's lymphoma, and hairy cell leukemia. Immunologic concepts are now used to classify NHLs. Identifying the cell of origin of a malignant lymphoma has important therapeutic implications, since malignant cells retain phenotypic and functional properties of their precursors. It is possible, therefore, to predict both the sites of involvement and the patterns of dissemination. Clinical applications are beginning to be developed. These include the use of monoclonal antibodies, monoclonal antibodies coupled to a toxin, alpha interferon, and monoclonal anti-idiotype antibodies. Human leukocyte interferon has been used experimentally to induce spontaneous regressions. Excellent results have been achieved so far only for patients with low-grade lymphomas.