Immediate postoperative radiotherapy or "watch and wait" in the management of adult low-grade glioma?

Abstract

Background: The EORTC Trial 22845 on the role of immediate postoperative radiotherapy in patients with supratentorial lowgrade glioma revealed an advantage of immediate postoperative radiotherapy for progression-free survival, but not for overall survival. It is still an open question in which clinical setting immediate radiotherapy should be considered and whether chemotherapy may become a useful alternative.

Material and methods: Reports in the literature spanning 60 years of radiation therapy were reviewed with respect to timing of radiotherapy, prognostic factors, dose prescriptions, modern treatment techniques, and late effects. Data on chemotherapy were also reviewed. Based on these data, the role of immediate postoperative radiotherapy or chemotherapy in adult low-grade glioma is presented.

Results: Radiotherapy is able to control symptoms in up to 80% of cases. Malignant transformation occurs in 36-86% of cases upon progressive disease. Long-term median survival crucially depends on prognostic factors and ranges between 12 months and 10 years. Radiotherapy does not cause neurocognitive deficits, provided that modern treatment techniques and moderate dose prescriptions are used. Recent series with small patient numbers indicate that chemotherapy using PCV or temozolomide may prolong median survival and induces response rates of 50% in oligodendroglial tumors.

Conclusion: The arguments for immediate postoperative irradiation include: low-grade gliomas respond to radiotherapy; the tumors often display an aggressive pathobiological behavior; patients with high risk profile may benefit from immediate radiotherapy in terms of progression-free and overall survival; modern focal radiotherapy is far less toxic than feared; radiotherapy might be more effective at diagnosis than at progression. Chemotherapy might be an alternative in immediate postoperative treatment. Its role, however, is unclear. The forthcoming prospective trial of the EORTC will address this issue in a randomized setting.