Secondary central nervous system involvement by non-Hodgkin's lymphoma: the risk factors.

The risk of secondary central nervous system (CNS) was estimated in 833 cases of non-Hodgkin's lymphoma diagnosed between January 1975 and December 1988. Fifty-one of them had CNS disease (51/833, 6.1 per cent). No case of low grade lymphoma developed CNS disease. However, 6.5 per cent and 16.7 per cent of patients with intermediate and high grade lymphomas, respectively, had secondary CNS involvement. Stage IV disease and the presence of B symptoms were also associated with an increased risk of CNS disease. Significantly higher incidence of CNS disease was seen in patients with lymphoma involving orbit (43 per cent), testis (40 per cent), peripheral blood (33 per cent), bone (29 per cent), nasal/paranasal sinuses region (23 per cent) and bone marrow (20 per cent). CNS prophylaxis is recommended to patients with an increased risk of CNS disease.