Radiotherapy and its impact on the nervous system of cancer survivors

Radiotherapy is routinely used for the treatment of nearly all brain tumors, but it may lead to progressive and debilitating impairments of cognitive function. The growing evidence supports the fact that radiation exposure to CNS disrupts diverse cognitive functions including learning, memory, processing speed, attention and executive functions. The present review highlights the types of radiotherapy and the possible mechanisms of cognitive deficits and neurotoxicity following radiotherapy. The review summarizes the articles from Scopus, PubMed, and Web of science search engines. Radiation therapy uses high-powered x-rays, particles, or radioactive seeds to kill cancer cells, with minimal damage to healthy cells. While radiotherapy has yielded relative success in the treatment of cancer, patients are often plagued with unwanted and even debilitating side effects from the treatment, which can lead to dose reduction or even cessation of treatment. Little is known about the underlying mechanisms responsible for the development of these behavioral toxicities; however, neuroinflammation is widely considered as one of the major mechanisms responsible for radiotherapy-induced toxicities. The present study reviews the different types of radiotherapy available for the treatment of various types of cancers and their associated neurological complications. It also summarizes the doses of radiations used in the variety of radiotherapy, and their early and delayed side effects. Special emphasis is given to the effects of various types of radiations or late side effects on cognitive impairments.