In 2 randomised, prospective Eastern Cooperative Oncology Group trials, the frequency of central nervous system (CNS) involvement after chemotherapy in 347 adults with stage III and IV unfavourable-histology, non-Hodgkin's lymphoma was 8·4%. The frequency varied from 0% in diffuse mixed lymphoma to >30% in lymphoblastic and diffuse-undifferentiated lymphoma. Of the 42% of patients who achieved complete remission after chemotherapy, CNS involvement developed in 5·4% during relapse, but in only 2·7% was the CNS the sole site of relapse. CNS lymphoma arose in 6·6% of 197 patients with diffuse histiocytic lymphoma, but in only 1 subject (1%) was the CNS the sole site of relapse. Therefore, CNS prophylaxis is not indicated for the common diffuse-histology subtypes of adult non-Hodgkin's lymphoma including diffuse-histiocytic, diffusemixed and diffuse poorly differentiated lymphocytic lymphoma. The relatively high frequency of CNS lymphoma in lymphoblastic and diffuse undifferentiated lymphoma justify further studies of CNS prophylaxis.
Bibliographical noteFunding Information:
We thank the Department of Infectious Diseases, Ruchill Hospital; colleagues in other hospitals for information about their patients; the Greater Glasgow Health Board, Glasgow District Council, Strathclyde Regional Council, and the Common Services Agency for access to data; Ms Ann Jones, Ms Pauline McLaughlan, Ms Patricia Burnett, and Ms Margaret Miller for home visits and record-keeping; and Mr C. Harvey for assistance with depriva- tion data. A. M. received a Junior Fellowship in Community Medicine from the Scottish Home and Health Department, and G. T. S. received support from the World Health Organisation (European Regional Office).