Cognitive deficits seen with radiotherapy for low-grade glioma


NEW YORK (Reuters Health), Aug 11 - Long-term survivors of low-grade glioma who were treated with radiotherapy show a progressive decline in attentional functioning not seen in their peers who were managed without radiotherapy, new research indicates.

Moreover, the cognitive deficits were linked to radiologic abnormalities and were seen even in patients treated with fraction doses that are typically considered safe (2 Gy or less), according to the report in the August 10 online issue of the Lancet Neurology.

In a prior study, Dr. Linda Douw, from VU University Medical Center, Amsterdam, and colleagues found evidence that the tumor itself, not the radiotherapy, was primarily responsible for cognitive deficits seen at six years. Only if the radiotherapy dose was greater than 2 Gy was there an added adverse effect on cognition.

In the present study, the research team examined cognitive outcomes in 65 patients at a mean of 12 years after diagnosis. Thirty-two patients received radiotherapy, including three patients at doses greater than 2 Gy.

Regardless of the dose given, radiation-treated patients had more deficits in attentional functioning than did patients not treated with radiation (p = 0.003). Worsening of executive functioning (p = 0.03) and information processing speed (p = 0.05) were also noted in the radiation group when comparing follow-up at six and 12 years.

Overall, 17 (53%) radiotherapy patients had cognitive deficits in five or more of the 18 neuropsychological test parameters compared with four (27%) of the radiotherapy-naïve patients.

The cognitive deficits seen in the radiotherapy group correlated with white-matter hyperintensities and global cortical atrophy on MRI, the researchers note.

The researchers "raise concerns that patients with low-grade glioma who were treated with what are now outdated radiotherapy techniques might develop long-term neurocognitive deficits, and this finding could inform the present-day and future management of these patients," Dr. Paul D. Brown and Dr. Jane H. Cerhan, from the Mayo Clinic, Rochester, MN, note in an accompanying editorial.

Lancet Neurol 2009.

Last Updated: 2009-08-10 11:16:05 -0400 (Reuters Health)

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