Adverse long-term effects of brain radiotherapy in adult low-grade glioma patients

Objective: To study the long-term effects of radiotherapy on cognitive func tion in adult patients operated on for low-grade glioma. Methods: A cohort of 160 patients who underwent surgery for low-grade gliomas of cerebral hem isphere between 1980 and 1992 in a single institution serving a defined pop ulation was studied. At a mean follow-up time of 7 years, 28 of the 101 pat ients who had postoperative irradiation (and no second surgery or chemother apy) were still alive and eligible for MRI and neuropsychological study. Tw enty-three of 59 patients who did not have radiotherapy, second surgery, or chemotherapy were alive and eligible at a mean of 10 years. Results: The g roup that had postoperative irradiation performed significantly worse than the group that did not in cognitive tests. This difference was not accounte d for by histologic diagnosis; location, extent of removal, or progression of the tumor; or any patient factor. Leukoencephalopathy was more severe in the group that had postoperative irradiation than in the group without rad iotherapy, and correlated to poor memory performances only in the postopera tive radiotherapy group. Average Karnofsky performance scale score was sign ificantly lower in the group that had postoperative irradiation than in the group that did not. Conclusion: In adults with low-grade glioma, postopera tive radiotherapy poses a significant risk of long-term leukoencephalopathy and cognitive impairment.