NEW YORK (Reuters Health) – New research indicates that with effective chemotherapy, children with acute lymphoblastic leukemia (ALL) do not need to receive prophylactic cranial irradiation.

Prophylactic cranial irradiation had once been a standard treatment for childhood ALL, but more and more clinicians are now replacing it with intrathecal and systemic chemotherapy in hopes of avoiding late radiation-associated complications, according to the report in The New England Journal of Medicine for June 25. Whether omitting cranial irradiation would increase the risks of relapse, however, was unclear.

To address this question, Dr. Ching-Hon Pui, from St. Jude Children’s Research Hospital, Memphis, Tennessee, and colleagues analyzed data from 498 children with newly diagnosed ALL. They compared the duration of continuous complete remission in 71 patients who were eligible for, but did not receive, cranial irradiation to the duration in 56 historical controls who received irradiation.

At 5 years, the rates of event-free and overall survival were 85.6% and 93.5%, respectively. The risks of isolated and any central nervous system relapse were 2.7% and 3.9%, respectively. All 11 patients who had an isolated CNS remission remained in second remission for 0.4 to 5.5 years, the report indicates.

Relative to historical controls given cranial irradiation, the study group that received currently recommended chemotherapy, but no irradiation had a significantly longer continuous complete remission.

Predictors of poorer event-free survival included CNS leukemia or a traumatic lumbar puncture with blast cells at diagnosis and a high degree of minimal residual disease following 6 weeks of remission induction. Correlates of CNS relapse included any CNS involvement at diagnosis, T-cell immunophenotype, and the TCF3-PBX1 genetic abnormality.

“The complete omission of prophylactic cranial irradiation allowed us to clearly identify risk factors for CNS relapse,” the authors note. However, “we would argue against the use of prophylactic cranial irradiation even in patients with these features because in our study, approximately 90% of such patients would have received unnecessary irradiation.”

Reference:
N Engl J Med 2009;360:2730-2741.