A small study analyzing neurocognitive function in women undergoing chemotherapy to treat their breast cancer shows that some of the common cognitive issues experienced by breast cancer patients tend to occur not only postchemotherapy, but also prior to chemotherapy treatment. The results of the study were presented at the San Antonio Breast Cancer Symposium (SABCS) held in Texas this week.
Bernadine Cimprich, PhD, RN, associate professor emerita at the University of Michigan School of Nursing and colleagues identified two factors—fatigue and neurocognitive compromise—that occurred before chemotherapy and affected the cognitive skills of the patients. These cognitive issues have previously been attributed mostly to chemotherapy, according to Cimprich.
“We have seen in our other studies that will be published soon that worry interfered with tasks for patients and worry was related to fatigue,” said Cimprich. “So we reasoned that perhaps psychological stress and fatigue could contribute to cognitive problems over time.”
The study tested neurocognitive responses of breast cancer patients using functional magnetic resonance imaging (fMRI). Cognitive function generally refers to mental tasks such as attention, speech, problem solving, decision-making, and memory, among others. The study included 28 women who received chemotherapy as an adjuvant therapy, 37 who received radiotherapy for their locally advanced cancer, and 32 noncancer subjects of the same age as the cancer patients. All participants went through verbal working memory skill tests and fMRI scanning both one month prior to treatment and one month after their specified treatment. In addition, fatigue was self-reported by all study subjects.
The chemotherapy patients reported the highest levels of fatigue and had the worst results from the cognitive tests, both pre- and post-chemotherapy, when compared to the participants in the other two groups. Higher levels of fatigue correlated with this poorer performance, according to the researchers. A stronger correlation was seen when the cognitive test was conducted after chemotherapy treatment. The radiotherapy-treated group had an intermediate cognitive function score, between that of the chemotherapy and healthy subject groups. The brain imaging results correlated with the cognitive tests.
The study did not show a cause and effect relationship but rather an association between cognitive impairment and fatigue and stress.
“It is a very well-designed study as they are looking at imaging, cognitive assessment, and fatigue both before and after chemotherapy,” said Tim A. Ahles, PhD, of the Neurocognitive Research Laboratory at the Memorial Sloan-Kettering Cancer Center in New York.
“We are not saying that all of these cognitive problems in these patients come from a single source,” said Cimprich. “What these data seem to suggest is that there are probably multiple sources of these problems—certainly chemotherapy is one of them, but we just don’t clearly yet understand what the independent effects of chemotherapy are.”
“What our data are showing is that women have problems with their working memory and attention before any treatment,” said Cimprich. Cimprich added that even patients who received only radiation therapy and no chemotherapy had some difficulties in cognitive tasks before their treatment.
Previous studies on the chemotherapy effects on the brain have thus far been inconclusive as far as the link between chemotherapy and cognitive function. While most breast cancer patients do tend to have some cognitive impairment, the extent of these cognitive issues is not clear—studies have shown that impairment can persist even post-treatment while other studies suggest that the impairment clears up. A recent meta-analysis compiled the results of 17 studies of cognitive function in breast cancer patients at least 6 months after their chemotherapy treatment. The results showed that the observed cognitive issues in patients with breast cancer who were previously treated with chemotherapy are fairly small and have to do with verbal and visual-spatial processing.
“There is actually an accumulating body of results that suggests there are a number breast cancer patients who have cognitive deficits based on neuropsychological testing and now emerging evidence that their brain functioning is dysregulated prior to treatment,” said Ahles. “The results are not yet completely consistent, they depend on the types of tasks tested, but the takeaway is that some of these cognitive deficits we thought were fully related to chemotherapy are detected prior to treatment.”
Cimprich believes that the level of worry may be key in impairing cognitive function in breast cancer patients prior to treatment. These symptoms may decrease with proper interventions such as exercise, psychological support, and other cognitive behavior interventions.
“There is a need for more critical awareness from physicians and nurses that these cognitive problems can begin before any adjuvant chemotherapy,” said Cimprich. “Since women awaiting chemotherapy are more vulnerable to these cognitive problems as well as higher levels of worry and fatigue, this may help identify women who are at even greater risk for these problems post-chemotherapy.”
“This cognitive impairment is a predictor in some studies. So those people who have the most cognitive problems pretreatment are the ones who are most vulnerable for long-term cognitive problems,” said Ahles.
