Prophylaxis and therapy of central nervous system involvement in adult acute lymphoblastic leukemia: recommendations of the Polish Adult Leukemia Group.

The central nervous system (CNS) is one of the most frequent extramedullary locations of adult acute lymphoblastic leukemia (ALL), affecting approximately 5% of patients at diagnosis. T-lineage ALL, high initial leukocyte counts and mediastinal involvement are the predisposing factors. In case of relapse, if no prophylaxis was administered, the rate of CNS involvement reaches 30-50%. As the prognosis of patients with isolated or mixed CNS relapse is particularly poor, adequate prophylaxis seems critical. The treatment comprises intrathecal cytostatics, cranial and spinal cord irradiation, as well as systemic chemotherapy including agents penetrating to the CNS. This strategy allows a reduction in CNS relapses to less than 5% of cases. Compliance to the prophylactic protocols should be one of the principles in the treatment of adult ALL.