An increased number of inflammatory cells in the brain is associated with cognitive complaints in cancer patients after their treatment. This is the conclusion of research by PhD student Gwen Schroyen (KU Leuven). For the first time, the increased amount of inflammatory cells could be clearly visualized in the brains of treated cancer patients.
It has been known for some time that some cancer patients can suffer from cognitive complaints after their treatment, even after they have been declared cured. For example, people experience difficulty in coming up with certain words, it is more difficult to multitask or lose their thread when they are briefly interrupted during a conversation. Patients also report that they are more distracted or less attentive, sometimes months or even years after the end of treatment. The complaints can occur with several types of cancer and with different types of treatment.
Previous research had already shown that the cognitive complaints were the result of an altered structure of the white matter pathways in the brains of patients. White matter pathways ensure that information can be exchanged between different parts of the brain. What caused this changed structure has not been clear until now.
The researchers tried to find an explanation for the phenomenon in an inflammatory reaction in the brain, because it is known that such a reaction is present in the rest of the body, in cancer and during treatment. Other studies also indicated these increased levels in the brains of rats or mice, when a tumor was present or during cancer treatment.
Doctoral student Schroyen’s team was able to set up such a study in humans for the first time. Thirty female breast cancer patients, fifteen of whom had finished chemotherapy a month ago and fifteen had received no chemotherapy, were tested. A control group of fifteen healthy people who had never had breast or other cancers was included in the study.
The brains of each person were imaged via scans and cognitive tests were administered. Logistically, it was not easy, says Schroyen. “What we have done is unique in our field. We were able to measure the activity of the inflammatory cells via PET scans. We were able to visualize where these cells are active with a tracer (a kind of ‘tracer’, ed.), which binds itself to, among other things, the inflammatory cells in the brain. And we needed arterial blood samples, which is an invasive procedure.”
The subjects who had received chemotherapy showed a markedly increased concentration of inflammatory cells in certain places in the brain. In addition, patients who scored worse on cognitive tests also had an increased inflammatory response in the frontal lobe of the brain, where people’s higher cognitive functions and personality traits are expressed, among other things.
“From this we concluded that inflammation in the brain may be associated with cognitive complaints in women treated for cancer,” says Schroyen. “The discovery is extremely valuable: for a long time it was thought that patients’ complaints ‘were only in their heads’ and that there was nothing structurally wrong. We were able to confirm previous animal research and showed that in certain patients an inflammatory response does occur in their brain, which may be related to the development of complaints.”