For which patients with aggressive non-Hodgkin's lymphoma is prophylaxis for central nervous system disease mandatory?

Purpose. Data of a multicenter study in non-Hodgkin's lymphoma (NHL) by the Dutch Hovon Group were reanalyzed to assess the risk of relapse in the central nervous system (CNS) related to the international risk index for NHL. In addition we assessed the risk for CNS disease in relation to the presence of bone marrow localisation at presentation. Design. We focused our analysis on those patients reaching a complete remission (CR). Two hundred eighty-six patients (histological subtypes D-H Working Formulation) and with stages II-IV were analyzed. One hundred ninety-three (67%) patients reached a CR. Results. Relapse occurred in 78 patients of whom 10 patients with concomitant or isolated CNS disease. According to the international risk index the following observations were made: low risk (n = 38) nine out of 34 CR relapsed, none had CNS involvement; low-intermediate risk (n = 115) 27 out of 83 CR relapsed, three had CNS involvement; high-intermediate risk (n = 110) 37 out of 68 CR relapsed, six had CNS involvement; high risk (n = 22) four out of seven CR relapsed, one had CNS involvement. Two out of 10 developed isolated CNS disease and eight out of 10 patients developed CNS disease with systemic relapse. Conclusion: Our data show that the number of CNS relapses after CR is relatively low (10 out of 193 = 5%), with an increasing incidence in the high-risk groups according to the international risk index. The occurrence of CNS relapse seems to be related to the risk of systemic relapse after CR. No subgroup could be discriminated in which prophylactic treatment would be of substantial benefit.