Service d’hématologie, hôpital Édouard-Herriot, Lyon, France
At the time of diagnosis, central nervous system (CNS) involvement is identified in less than 10% of adult acute lymphoblastic leukemia (ALL). Long-term disease-free survival can be achieved in these patients. CNS disease at presentation does not appear to be an independent poor prognostic factor. In CNS leukemia, innovative treatments and alternative delivery techniques are, however, warranted. Outcome in such patients is a reflection of an aggressive systemic and CNS-directed therapy. However, CNS toxicity represents the dose-limiting side effect of treatment. With effective CNS prophylaxis including intrathecal chemotherapy, high-dose systemic administration of certain agents and cranial irradiation, most adults with ALL without CNS disease at diagnosis may remain free of CNS leukemia. CNS involvement at the time of relapse occurs in 1 to 15% of cases. Leukemic relapse remains a major therapeutic challenge. Adult ALL with CNS recurrence remains of poor prognosis and is generally associated with a systemic and medullary relapse.