Treatment and Survival of Low-Grade Astrocytoma in Adults--1977–1988

Is there a place for radiotherapy in low-grade gliomas?

The optimal management of supratentorial low-grade glioma remains controversial, and only limited definitive data is available to guide recommendations. Treatment decisions have to take into account both the management of symptoms and of tumour control, and must balance the benefits against the potential for treatment-related complications. Overall outcome is more dependent on patient and tumour-related characteristics such as age, tumour grade, histology and neurological function than treatment. From the pooled analysis of 2 randomized EORTC trials a prognostic score has been derived, median survival is varying from 3.2 to 7.8 years. Radiation therapy is usually the primary treatment modality; however its benefit on initial tumour control may be outweighed by potential late toxicity. To date only 4 large randomized trials in patients with low-grade glioma have been reported. It allows concluding that early radiotherapy does not improve overall survival and supports an initially expectative approach. Similarly, higher radiation doses above 45-50 Gy (fractions of 1.8-2.0 Gy) do not confer a better outcome but may be associated with increased toxicity. The adjuvant use of PCV-chemotherapy in high-risk patients also failed to improve progression-free and overall survival. An ongoing large randomized EORTC/NCIC trial is investigating the primary treatment with temozolomide chemotherapy versus standard radiotherapy in patients "at need for treatment". Tumour material will be collected in all patients, which ultimately may allow identifying on a molecular basis patients for whom one or another treatment strategy may fit best. Irrespective of new chemotherapeutic agents, radiotherapy is also evolving. Highly conformal techniques based on modern imaging as co-registered MRI scans, limiting the amount of normal tissue irradiated without compromising tumour control, will be the future approach in order to reduce neurotoxicity.

The role of stereotactic radiosurgery for low-grade astrocytomas

OBJECT

This study was conducted to examine the role of radiosurgery in the management of patients with recurrent or unresectable low-grade astrocytomas.

METHODS

During a 13-year interval, 49 patients underwent stereotactic radiosurgery as part of multimodal treatment of their recurrent or unresectable low-grade astrocytomas. Thirty-seven of these patients (median age 14 years) harbored pilocytic astrocytomas and 12 patients harbored World Health Organization (WHO) Grade II fibrillary astrocytomas (median age 25 years). Tumors involved the brainstem in 22 cases, cerebellum in four, thalamus in six, temporal lobe in five, frontal lobe in four, and parietal lobe in three, as well as the hypothalamus, corpus callosum, insular cortex, optic tract, and third ventricle in one patient each. Each diagnosis was confirmed with the aid of stereotactic biopsy sampling in 17 patients, open biopsy sampling in five, partial resection in 13, and near-total resection in 14. Multimodal treatment included fractionated radiotherapy in 14 patients, stereotactic intracavitary irradiation in five, chemotherapy in two, cyst drainage in eight, ventriculoperitoneal shunt placement in five, and additional cytoreductive surgery in five. Tumor volumes ranged from 0.42 to 45.1 cm3. The median radiosurgical dose to the tumor margin was 15 Gy (range 9.6-22.5 Gy). After radiosurgery, serial neuroimaging demonstrated complete tumor resolution in 11 patients, reduced tumor volume in 12, stable tumor volume in 10, and delayed tumor progression in 16. No procedure-related death was encountered. Forty-five of 49 patients are alive at a median follow-up period of 32 months after radiosurgery and 63 months after diagnosis. Sixteen patients participated in follow-up review for more than 60 months. Three patients died of local tumor progression.

CONCLUSIONS

Stereotactic radiosurgery is a potential alternative or adjunctive intervention in the management of selected patients with pilocytic or WHO Grade II fibrillary astrocytomas, usually performed for small-volume tumors in an attempt to avoid larger-field fractionated radiotherapy.