Radiotherapy associated with long-term cognitive deterioration in survivors of low-grade glioma

More than half of patients with low-grade glioma who received treatment with radiotherapy had cognitive disabilities compared with only 27% of patients who did not receive radiotherapy, according to data from a long-term follow-up study conducted in the Netherlands. Patients who received fraction doses of 2 Gy or less also experienced a decrease in attentional functioning, researchers found.

In a previous study of 195 patients with low-grade glioma, the researchers reported that six years postdiagnosis all patients had cognitive disability compared with a control group; however, those patients who received high-dose radiation (2 Gy or more) had additional cognitive deterioration.

The current study, which included 65 patients with low-grade glioma, followed patients for a median of 12 years after first diagnosis. Patients received follow-up cognitive assessments in six domains: attention, executive functioning, verbal memory, working memory, psychomotor functioning and information processing speed. The researchers rated white-matter hypertensities and global cortical atrophy on MRI scans. Forty-nine percent of patients underwent radiotherapy; three patients had fraction doses greater than 2 Gy.

Regardless of radiotherapy fraction dose, at the second follow-up patients who had received radiotherapy had more attentional deficits that affected functioning than those patients who did not have radiotherapy (–1.6 vs. -0.1; P=.003). Executive functioning (–2.0 vs. –0.5; P=.03) and information processing speed deficits (–2.0 vs. –0.6; P=.05) were also worse among patients who underwent radiotherapy.

“Our results suggest that the risk of long-term cognitive and radiological compromise that is associated with radiotherapy should be considered when treatment is planned,” the researchers wrote.

Douw L. Lancet. 2009;doi:10.1016/S1474-4422(09)70204-2.