Non-Hodgkin's lymphomas--current status of therapy and future perspectives

Non-Hodgkin's lymphomas (NHL) are a heterogeneous group of disorders which can either be classified according to their biology, represented by corresponding counterparts of normal lymphocyte development as in the Kiel classification, or according to their clinical course, used in the Working Formulation. The recently proposed Revised European-American Lymphoma (R.E.A.L.) classification may unify both aspects and facilitate the comparability of international studies. Besides histology, the extent of disease still comprises the major determinant of therapy. In high-grade lymphomas combination chemotherapy with cyclophosphamide, hydroxydaunorubin, vincristine and prednisone (CHOP) represents the treatment of first choice, and may be restricted to 3-4 cycles in patients with limited stages of the disease when followed by involved field radiotherapy. In more extended, bulky stage II to IV disease, treatment must be extended to six courses of CHOP and, potentially, additional irradiation. Even in advanced states of the disease, long-term remission and potential cure are achieved in 30-50% of cases. In low-grade lymphomas, most patients present with advanced stages III and IV for which chemotherapy can be applied with palliative intention only. Hence, a watch-and-wait approach still seems appropriate outside clinical investigations until the disease requires a therapeutic intervention. This consists preferentially of chemotherapy of moderate intensity such as cyclophosphamide, vincristine and prednisone (COP) or prednimustine and mitoxantrone (PmM). In responding patients, maintenance therapy with interferon-alpha is currently being explored and may result in prolongation of disease-free and, possibly also, overall survival. In both high- and low-grade lymphomas, intensification of therapy by myeloablative chemotherapy or combined chemoradiotherapy followed by autologous bone marrow transplantation (ABMT) or peripheral stem cell transplantation provides a promising and potentially curative prospective. In addition, new cytostatic agents such as the purine analogues--fludarabine, chlorodeoxyadenosine and deoxycoformycin--enlarge the therapeutic spectrum. More experimental approaches consist of the application of immunotoxins or radioisotypes, coupled to monoclonal antibodies directed against lymphoma-specific antigens. Overall, the substantial advances that have been achieved in the understanding of the biology and pathogenesis of malignant lymphomas, as well as the current achievements of therapy and the new promising perspectives, justify the hope that curative therapy can soon be offered to an increasing proportion of patients with NHL.