Central nervous system relapse in malignant lymphomas: risk factors and implications for prophylaxis.

The records of 292 patients with malignant lymphoma other than Hodgkin's disease, registered in our protocols from 1967 to 1977, were reviewed to identify those with central nervous system (CNS) involvement. Thirty-one patients were encountered with this complication, an incidence of 11%. Patients with a diffuse histology had a higher frequency of CNS recurences (27/174 = 16%) in contrast to only 4/118 (3%) for those with nodular types. However, if only patients with diffuse histology in CR are considered, the frequency of CNS relapse is 13.5% (13/98). The risk factors that predict for the development of this complication were studied using multivariate analysis. Diffuse poorly differentiated lymphocytic and diffuse undifferentiated lymphomas were found to be associated with a high risk of CNS relapse. Prior chemotherapy, bone marrow involvement, age less than 35, and extranodal disease were also identified as high-risk factors. Using the information generated by a logistic regression model, patients with malignant lymphoma of diffuse type can be classified into three categories when first seen: low-risk group, intermediate, and high-risk group. CNS prophylaxis is recommended for the intermediate and high-risk group, while only close follow-up is advised for the low-risk group patients who have one adverse characteristic.