✓ Low-grade gliomas constitute the largest group of cerebral hemispheric tumors in the pediatric population. Although complete tumor resection is generally the goal in the management of these lesions, this can prove difficult to achieve because tumor margins may blend into the surrounding brain. This raises several important questions on the long-term behavior of the residual tumor and the role of adjuvant therapy in the management of these lesions.
To examine these issues, the authors reviewed their experience in 71 children with low-grade cerebral hemispheric gliomas who were treated at their institution between 1956 and 1991 and assessed the relationship between clinical, radiographic, pathological, and treatment-related factors and outcome. Only seven patients in the series died, one from perioperative complications, five from progressive disease, and one (a child with neurofibromatosis) from a second neoplasm. For the 70 patients who survived the perioperative period, overall actuarial survivals at 5, 10, and 20 years were 95%, 93%, and 85%, respectively; progression-free status was maintained in 88%, 79%, and 76%, respectively. On univariate analysis, the factor that was most strongly associated with both overall and progression-free survival was the extent of tumor resection (p = 0.013 and p = 0.015, respectively). A relationship between extent of resection and progression-free survival was present both in patients with pilocytic astrocytomas (p = 0.041) and those with nonpilocytic tumors (p = 0.037). Histopathological diagnosis was also associated with overall survival on univariate analysis; poorer results were seen in the patients with nonpilocytic astrocytoma compared to those with other low-grade gliomas, such as pilocytic astrocytoma, mixed glioma, and oligodendroglioma (p = 0.021). The use of radiotherapy was not associated with a significant improvement in overall survival (p = 0.6). All three patients who ultimately developed histologically confirmed anaplastic changes in the vicinity of the original tumor had received prior radiotherapy, 20, 46, and 137 months, respectively, before the detection of malignant progression. In addition, children who received radiotherapy had a significantly higher incidence of late cognitive and endocrine dysfunction than the nonirradiated patients (p < 0.01 and 0.05, respectively).
The authors conclude that children with low-grade gliomas of the cerebral hemispheres have an excellent overall prognosis. Complete tumor resection provides the best opportunity for long-term progression-free survival. However, even with incomplete tumor excision, long-term progression-free survival is common. The findings in this study do not support the routine use of postoperative radiotherapy after an initial incomplete tumor resection: although irradiation appears to increase the likelihood of long-term progression-free survival, overall survival is not improved significantly, and long-term morbidity may be increased.