Changes in cortical thickness and volume after cranial radiation treatment: A systematic review

• Published in: Radiotherapy and oncology 2019-06, Vol.135, p.33-42
• Main Authors: Nagtegaal, Steven H.J., David, Szabolcs, van der Boog, Arthur T.J., Leemans, Alexander, Verhoeff, Joost J.C.
• Format: Article
• Language: English
• Subjects: Animals; Brain neoplasms; Cerebral cortex; Cerebral Cortex - diagnostic imaging; Cerebral Cortex - pathology; Cerebral Cortex - radiation effects; Cognition - radiation effects; Cranial Irradiation; Humans; Magnetic Resonance Imaging - methods
• ISSN: 0167-8140; 1879-0887
• DOI: 10.1016/j.radonc.2019.02.013

•New RT innovations enable sparing of brain areas susceptible to radiation damage.•Interest in the effect of radiation therapy on the cerebral cortex has increased.•We found papers with great heterogeneity and lacking in methodological strength.•More robust research is needed to make recommendations for clinical practice. Cognitive decline has a clear impact on quality of life in patients who have received cranial radiation treatment. The pathophysiological process is most likely multifactorial, with a possible role for decreased cortical thickness and volume. As radiotherapy treatment systems are becoming more sophisticated, precise sparing of vulnerable regions and tissue is possible. This allows radiation oncologists to make treatment more patient-tailored. A systematic search was performed to collect and review all available evidence regarding the effect of cranial radiation treatment on cortical thickness and volume. We searched the Pubmed, Embase and Cochrane databases, with an additional reference check in the Scopus database. Studies that examined cortical changes on MRI within patients as well as between treated and non-treated patients were included. The quality of the studies was assessed with a checklist specially designed for this review. No meta-analysis was performed due to the lack of randomised trials. Out of 1915 publications twenty-one papers were selected, of which fifteen observed cortical changes after radiation therapy. Two papers reported radiation-dependent decrease in cortical thickness within patients one year after radiation treatment, suggesting a clear relation between the two. However, study quality was considered mostly suboptimal, and there was great inhomogeneity between the included studies. This means that, although there has been increasing interest in the effects of radiation treatment on cortex morphology, no reliable conclusion can be drawn based on the currently available evidence. This calls for more research, preferably with a sufficiently large patient population, and adequate methodology.