CNS involvement in ALL

CNS involvement at the time of diagnosis is observed in <5% of children and in <10% of adults with ALL (1).

CNS prophylaxis has been identified as the single best approach in treating patients with CNS leukaemia.

Without CNS prophylaxis

• 50-75% of patients eventually will develop CNS disease
• CNS recurrence occurs in approximately 30 - 50% of patients who have achieved complete remission (1)

CNS recurrence is associated with a poor prognosis (1).

CNS relapse has been observed in 30-40% of initial relapses in some studies (1).

The following factors are associated with an increased risk of CNS relapse:

• a T-cell immunophenotype
• hyperleucocytosis
• high-risk genetic abnormalities
• presence of leukaemic cells in cerebrospinal fluid

Due to the associated acute and late complications (e.g. - second cancers, late neurocognitive deficits, and endocrinopathy), cranial irradiation is limited to patients who are at high risk of a CNS relapse (1,2).

Intrathecal and systemic chemotherapy have replaced cranial irradiation (1).

• triple intrathecal therapy with methotrexate, cytarabine, and hydrocortisone is effective in preventing CNS relapse (2)

Reference:

• 1. Surapaneni UR et al. Central nervous system relapse in adults with acute lymphoblastic leukemia. Cancer. 2002;94(3):773-9.
• 2. Pui CH, Robison LL, Look AT. Acute lymphoblastic leukaemia. Lancet. 2008;371(9617):1030-43.