Acute lymphoblastic leukemia (ALL) 5-year survival rates are approaching 90% in children and 50% in adults who are receiving contemporary risk-directed treatment protocols. Current efforts focus not only on further improving cure rate but also on patient quality of life. Hence, all protocols decrease or limit the use of
cranial irradiation as central nervous system (CNS)-directed
therapy, even in patients with high-risk presenting features, such as the presence of
leukemia cells in the cerebrospinal fluid (even resulting from traumatic lumbar puncture), adverse genetic features, T-cell immunophenotype, and a large
leukemia cell burden. Current strategies for CNS-directed
therapy involve effective systemic
chemotherapy (eg,
dexamethasone, high-dose
methotrexate, intensive
asparaginase) and early intensification and optimization of intrathecal
therapy. Options under investigation for the treatment of relapsed or refractory CNS
leukemia in ALL patients include
thiotepa and intrathecal liposomal
cytarabine. CNS involvement in
non-Hodgkin lymphoma (NHL) is associated with young age, advanced stage, number of extranodal sites, elevated
lactate dehydrogenase, and International Prognostic Index score. Refractory CNS
lymphoma in patients with NHL carries a poor prognosis, with a median survival of 2 to 6 months; the most promising treatment, autologous stem cell transplant, can extend median survival from 10 to 26 months. CNS prophylaxis is required during the initial treatment of NHL subtypes that carry a high risk of CNS relapse, such as B-cell ALL,
Burkitt lymphoma, and
lymphoblastic lymphoma. The use of CNS prophylaxis in the treatment of
diffuse large B-cell lymphoma is controversial because of the low risk of CNS relapse ( approximately 5%) in this population. In this article, we review current and past practice of intrathecal
therapy in ALL and NHL and the risk models that aim to identify predictors of CNS relapse in NHL.