First, it remains uncertain whether the risk of disease progression in children with low-grade hemispheric gliomas is influenced by the extent of tumor resection32,33,39,43,56,61 and whether, as in adults with low-grade gliomas,19,32,39,43,44,56,61 there is a significant incidence of late tumor recurrence even in those patients who undergo a presumed gross total tumor resection. Second, studies involving adults with low-grade hemispheric astrocytomas have generated conflicting results regarding the efficacy of radiotherapy in controlling residual disease.6,19,22,25,32,33,39,41,43,44,50,52,54,56–59,61,64,66 In those studies in which a benefit has been found,6,19,22,32,33,43,56,57,59,64 it has often been limited to individuals in poor prognostic groups, such as older patients or those with subtotal tumor removal. The benefit of this modality for pediatric hemispheric low-grade glioma is even less clear.3,12, 24,26,34,36,37,41,53,54 In view of the well-known risks of radiation therapy to the developing nervous system,9,13,14,16,29,60 it is essential to be certain that this treatment, when employed, is effective in improving outcome. Although attempts have been made to examine this issue in a prospective, randomized multiinstitutional study format, such investigations have been severely hampered by difficulties in the accrual of patients who are randomly assigned to radiotherapy versus no radiotherapy treatment arms. Third, the contribution of histological subtype, for example, pilocytic versus nonpilocytic astrocytoma, to long-term outcome in pediatric supratentorial low-grade gliomas remains undefined. Although there is a suggestion that adults with hemispheric pilocytic astrocytomas fare better than those with nonpilocytic astrocytomas7,21,22,41,56 and that children with pilocytic cerebellar astrocytomas have a better prognosis than those with diffuse, nonpilocytic cerebellar astrocytomas,23,67 comparable studies involving pediatric hemispheric gliomas have been lacking in the literature. Finally, the long-term incidence of malignant progression in low-grade hemispheric gliomas of childhood remains uncertain. Although 13.3% to 32% of adult low-grade astrocytomas will manifest malignant histological features within 5 to 10 years of diagnosis, and as many as 79% of progressive tumors will become malignant histologically,32,38,43,44,49,61,62 anaplastic progression of pediatric low-grade gliomas appears to be comparatively uncommon.10,26,37,41,65
To study these issues, we reviewed overall survival, progression-free survival, and functional outcome in 71 children with low-grade hemispheric astrocytomas, oligoastrocytomas, and oligodendroglioma managed at the Children's Hospital of Pittsburgh between 1956 and 1991. Other common supratentorial glial neoplasms such as gangliogliomas and gliomas of the thalamus and optic pathways were excluded from this study because they are likely to constitute prognostically distinct groups.
The authors wish to thank Dr. Leland Albright for reviewing the manuscript and Barbara Zarenek for assistance with obtaining updated patient follow-up information through the Children's Hospital of Pittsburgh Tumor Registry.
Mantel N: Evaluation of survival data and two new rank order statistics arising in its consideration. Cancer Chemother Rep 50:163–1701966Mantel N: Evaluation of survival data and two new rank order statistics arising in its consideration. Cancer Chemother Rep 50:
Piepmeier JM: Observations on the current treatment of low-grade astrocytic tumors of the cerebral hemispheres. J Neurosurg 67:177–1811987Piepmeier JM: Observations on the current treatment of low-grade astrocytic tumors of the cerebral hemispheres. J Neurosurg 67:
The results of this study were presented in part at the 22nd Annual Meeting of the Pediatric Section of the American Association of Neurological Surgeons, San Antonio, Texas, December 10, 1993, and the 62nd Annual Meeting of the American Association of Neurological Surgeons, San Diego, California, April 11, 1994.