Prophylactic Central Nervous System Irradiation Is Not Indispensable in Adult Patients with Acute Lymphoblastic Leukemia: A Multicenter Retrospective Cohort Study

Objective: Studies comparing the efficacy and safety of prophylactic regimens for central nervous system (CNS) involvement in acute lymphoblastic leukemia (ALL) are scarce in adults. This multicenter retrospective study aimed to compare the efficacy of prophylactic regimens with and without CNS irradiation on the development of CNS relapse during follow-up. Materials and Methods: This was a multicenter comparative cohort study. A total of 203 patients were included from four tertiary care centers in Turkey. Patients were divided into two groups according to whether they received CNS irradiation or not. The groups were analyzed retrospectively regarding patient and disease characteristics, with the main focus being CNS relapse. Results: While 105 patients received chemotherapy-based prophylaxis, 98 patients received additional CNS irradiation. These groups were statistically comparable in terms of demographic characteristics and risk factors for CNS involvement. In the irradiation group, patients were younger and had more stem cell transplants. In a median of 23.8 (11.1-62.4) months, there was no difference between the two groups regarding CNS relapse-free survival (log-rank p=0.787). Conclusion: Craniospinal irradiation may not be indispensable for every adult patient with ALL, similarly to pediatric patients. It is crucial to avoid the long-term toxicities of radiation, especially in patients with long life expectancy. Craniospinal irradiation may be reserved for therapeutic use in cases of CNS relapse and prophylaxis for some high-risk patients.