Craniospinal irradiation for acute lymphoblastic leukemia with central nervous system disease at diagnosis: a report from the Children's Cancer Group.

PURPOSE: This study attempted to determine if central nervous system (CNS) disease at diagnosis is a poor prognostic factor in children with acute lymphoblastic leukemia (ALL) and whether 6 Gy of spinal irradiation is an adequate dose for these patients. METHODS AND MATERIALS: Previously the Children's Cancer Group (CCG) treated patients with ALL and CNS disease at diagnosis with cranio (24 Gy)-spinal (12 Gy) irradiation, as well as systemic and intrathecal chemotherapy. In a series of CCG trials completed in 1989 the spinal dose was empirically reduced to 6 Gy for patients receiving systemic chemotherapy with an intensive consolidation phase to limit hematopoietic toxicity. The spinal dose was left at 12 Gy for patients treated with a less intensive consolidation phase.
RESULTS: With a median follow-up for surviving patients of 74 months, the 5-year event-free survival for 53 patients with CNS disease at diagnosis was 69 +/- 13% (+/- 2 standard deviations), similar to the value obtained for 3364 patients without CNS disease, 67 +/- 2%. Corresponding values for 5-year survival were 77 +/- 12% and 80 +/- 1%, and for freedom from isolated first CNS relapse, were 90 +/- 9% and 94 +/- 1%. Event-free survival, survival, and freedom from isolated first CNS relapse in the 6-Gy group were as good as in the 12-Gy group.
CONCLUSION: CNS disease at diagnosis is not a poor prognostic factor for children with ALL who are treated with intensive systemic chemotherapy, craniospinal irradiation, and intrathecal chemotherapy. Six Gy is an adequate dose of spinal irradiation for these patients.