Outcome of adult ALL with central nervous system (CNS) involvement is not clearly defined. We studied 104 patients presenting with CNS involvement at diagnosis among 1493 patients (7%) included into the LALA-87 or LALA-94 trials, and 109 patients (9% of first remitters) presenting CNS disease at the time of first relapse among the 709 relapsing patients (15%) included initially in these trials. Treatment of patients presenting CNS involvement at diagnosis consisted in initial chemotherapy completed by 18 double or triple intrathecal injections associated with 15 to 20 Gy cranial irradiation, followed when possible by intensification by allogeneic or autologous stem cell transplantation (SCT). At diagnosis, 43 patients (41%) presenting with CNS involvement had T-lineage ALL, 53 (51%) had B-lineage ALL (of whom 9 were diagnosed as Philadelphia (Ph) chromosome positive ALL), 8 had undifferentiated ALL or unknown immunophenotype. Eighty-seven of 104 (84%) patients with CNS involvement at diagnosis achieved complete remission (CR). Fifty-three patients underwent SCT (25 allogeneic SCT from matched related or unrelated donor, 28 autologous SCT). Overall survival at 7 years was 34% in those with CNS involvement at diagnosis versus 29% (p = NS) for those without. DFS at 7 years was 35% versus 28% (p = NS). There were no significant differences between patients with CNS involvement and those without CNS involvement regarding T lineage ALL, B lineage ALL (including or not Ph ALL). There were also no significant differences regarding patients who underwent transplantation as consolidation intensification, while in patients receiving only chemotherapy patients without initial CNS involvement had a better outcome (p = 0.01). Among the 709 patients with primary relapse, 66 patients (61%) presented a CNS relapse combined with bone marrow relapse, whereas 17 relapses (15%) and 26 relapses (24%) were CNS relapses combined with another extramedullary relapse or isolated CNS relapses respectively. Median time to relapse was 6.7 months (range, 1–62) in patients with CNS relapse versus 11.2 months (1.7–111) in relapsing patients without CNS involvement. Eleven patients (10%) with CNS relapse had CNS involvement at diagnosis, while 98 patients were diagnosed with CNS disease only at the time of first relapse. Overall, 38 out of 109 patients with CNS relapse (35%) achieved CR. The median OS was 6.3 months. Outcome was similar in terms of CR proportion and OS in relapsing patients without CNS involvement. The 2-year OS rates did not show any difference among patients with CNS relapse who had CNS involvement at diagnosis and those with CNS disease only diagnosed at the time of first relapse.Overall, CNS leukemia in adult ALL is uncommon at diagnosis. Patients have a similar outcome than those who did not present with CNS involvement. However, patients benefit from intensification therapy by autologous or allogeneic SCT. CNS leukemia at first relapse are also uncommon but probably underestimated. Outcome is particularly poor as this of all adult ALL in first relapse.

Author notes

Disclosure: No relevant conflicts of interest to declare.