Outcome analysis of childhood low-grade astrocytomas

Background. We aimed to determine the long-term natural history of low-grade astrocytomas (LGA) in children, with respect to pathology, and to evaluate influence of treatment on survival. Patients and Methods. A consecutive cohort of patients <= 21 years with surgically confirmed LGA from 1965 to 1996 was assembled. All available pathology specimens were reviewed, masked to original diagnosis, patient data, and neuroimaging. Results. Two hundred seventy-eight children (160 males; mean age 9.1 years; tumor location: 77 cerebrum, 62 cerebellum, 51 hypothalamic, 30 thalamus, 9 ventricle, 40 brainstem, and 9 spine) were assessed. Among 246 specimens reviewed, diagnoses were 135 pilocytic astrocytoma (PA), 27 diffuse astrocytoma (DA), 75 unclassifiable well-differentiated astrocytoma (NOS), and 9 subependymal giant cell astrocytoma. At 5 and 10 years from initial surgery, for all LGA overall survival (OS) was 87% and 83%, while progression-free survival (PFS) was 55% and 42%, respectively. Original pathology diagnoses did not predict PFS (P=0.47), but reviewed diagnoses were significantly associated with PFS (P=0.007). Reviewed diagnoses were highly associated with OS (P < 0.0001), with 5-year OS for PA 96%, DA 48%, and NOS 86%; these differences remained significant when stratified by location or extent of resection. Among patients with residual tumor after surgery, 5-year PFS was 48% with observation alone (n=114), no different (P=0.32) from that achieved with immediate irradiation (n=86). Conclusion. LGA, particularly PA, have excellent long-term OS. While tumor location and resection extent affect outcome, pathologic diagnosis when carefully interpreted significantly influences long-term survival. Immediate postoperative irradiation does not confer an advantage in delaying first progression in children with residual PA.