Radiation therapy contributes to cognitive impairment in cancer survivors

Researchers at the University of Minnesota College of Veterinary Medicine, along with partners from the Medical School and the Masonic Cancer Center, have identified how chemotherapy and radiation treatment contribute to cognitive decline in cancer survivors.

Cancer-related cognitive impairment can affect learning, understanding, language, memory, and a feeling of well-being. Up to 75 percent of cancer survivors experience some form of cognitive impairment during and up to 10 years after treatment—even during remission. Experts have not understood the specific roles of chemotherapy and radiation in this cognitive disruption, and this lack of information has stalled the development of effective prevention or therapy.

To fill this knowledge gap, the researchers used a mouse model to observe and compare how radiation, chemotherapy, and simultaneous radiation and chemotherapy treatment impacted cognition and brain inflammation. 

The team found that different regions of brain inflammation were observed in each treatment group. However, compared to no treatment, radiation, chemotherapy, and simultaneous treatment led to the same degree of memory deficits. Chemotherapy alone led to additional brain inflammation compared to the other treatment groups.   

These findings not only confirm that radiation aimed at sites that are distant from the brain can cause brain inflammation, but that the treatment also causes significant cognitive deficits. The research also identifies distinct immune responses in the brain that followed the treatments and associates those changes with specific cognitive deficits. 

“This research is important since more than 50% of human cancer patients receive radiation therapy with chemotherapy,” says Kim Demos-Davies, a DVM and PhD student at CVM who led the study. “It was previously recognized that chemotherapy causes cognitive changes, but we now know radiation contributes to brain changes, too—even though it is typically a local type of treatment. Understanding how these treatments lead to different detrimental effects in the brain can help us identify new therapies that prevent cognitive symptoms in cancer survivors.”

Read the full study in Frontiers.