An article published Online first and in an upcoming edition of The Lancet Neurology reports that although low doses of radiotherapy are considered as safe; they may contribute to progressive cognitive decline in patients with low-grade glioma brain tumours.
The most common type of brain cancer is Low-grade glioma (LGG) brain tumour. Early or delayed radiotherapy is the most frequent treatment. But still, there are many questions about the best treatment approach. Over time radiotherapy can cause damage to the brain. Since the average survival time for patients with LGG is ten years, these patients are at significant risk of developing late or delayed radiation injuries.
The authors established from an earlier study that usually after six years following diagnosis, high-level radiation treatment and the tumour itself were related with cognitive impairment. But the effects of local radiotherapy on cognitive function in long-term survivors of LGG are not identified.
Linda Douw from VU University Medical Center, in Amsterdam, Netherlands and her collaborators give an account in this study of the long-term radiological and cognitive abnormalities in survivors of LGG from the original study.
From a total of 65 patients with stable disease since the first assessment, around half had received radiotherapy. An average of twelve years after treatment, they all had a follow-up cognitive assessment. In order to identify differences between patients who were given radiotherapy and those who were not, researchers considered:
• Attention
• Executive functioning
• Verbal memory
• Working memory
• Psychomotor functioning
• Information processing
Overall, 27 percent of patients who did not have radiotherapy had cognitive disability compared with 53 percent of those who had been given radiotherapy.
In general, patients given radiotherapy had poorer skills at attention functioning, executive functioning, and information processing speed than patients not given radiotherapy. There was confirmation that the patients who did not have radiotherapy presented stable radiological and cognitive status.
The authors explain that: “By contrast with the results of our earlier study, the current results indicate that radiotherapy is associated with long-term cognitive deterioration, regardless of fraction dose…[and indicate that] all surviving patients who had radiotherapy are at risk of developing attentional problems, not just those who were given a high-level dose”.
They say in closing that treating patients who have LGG with radiotherapy should be measured cautiously. They advise that deferring treatment might be the treatment plan that is most favourable to cognitive status and quality of life.
In an associated Reflection and Reaction comment, Paul Brown and Jane Cerhan from the Mayo Clinic in Rochester, USA, remark that since the 1970s when the treatment period started in the study, there has been significant progress in radio-therapeutic techniques. For that reason they warn that it is not viable to draw definite conclusions from these results about the risks of modern radiotherapy.
They carry on by claiming there is a need for further trials to evaluate the effects of modern radiotherapy techniques on cognitive function in patients with LGG.
“Cognitive and radiological effects of radiotherapy in patients with low-grade glioma: long-term follow-up”
Linda Douw, Martin Klein, Selene S A A Fagel, Josje van den Heuvel, Martin J B Taphoorn, Neil K Aaronson, Tjeerd J Postma, W Peter Vandertop, Jacob J Mooij, Rudolf H Boerman, Guus N Beute, Jasper D Sluimer, Ben J Slotman, Jaap C Reijneveld, Jan J Heimans
DOI: 10.1016/S1474-4422(09)70204-2
“Same, better, or worse? Neurocognitive effects of radiotherapy for low-grade gliomas remain unknown”
Paul D Brown, Jane H Cerhan
DOI: 10.1016/S1474-4422(09)70205-4
Written by Stephanie Brunner (B.A.)