Cognitive complaints by breast cancer patients have scientific basis
Many breast cancer patients complain for years following treatment about decreased cognitive functioning, including problems with memory, concentration and mental "fogginess". Whether such complaints are psychosomatic or physiological as a result of changes in brain functioning have long been a subject of debate among physicians and other healthcare professionals.
According to a new study published online April 18 in the Journal of the National Cancer Institute, there is indeed a significant correlation between poorer performance on neurological tests and memory complaints in post-treatment, early-stage breast cancer patients, especially those who underwent both chemotherapy and radiation.
The study was led by Dr. Patricia Ganz, director of cancer prevention and control research at UCLA's Jonsson Comprehensive Cancer Center, who found that there was a scientific basis for the mental fogginess so many cancer patients complain about.
"The study is one of the first to show that such patient-reported cognitive difficulties, often referred to as 'chemo brain' in those who have had chemotherapy, can be associated with neuropsychological test performance," said Dr. Ganz, who is also a professor of health policy and management at UCLA's Fielding School of Public Health and a professor of medicine at the David Geffen School of Medicine at UCLA.
For the study, Ganz and her research team looked at 189 breast cancer patients. All of the patients had enrolled in the study about one month following completion of their initial breast cancer treatments, but before they began endocrine hormone-replacement therapy, which approximately 70 percent planned to start. The average age of the patients was 52, with two-thirds of them having had breast-conserving surgery. More than half the women had received chemotherapy, and three-quarters of them had radiation.
Since cognitive complaints in breast cancer patients post-treatment often include anxiety and depression – reducing confidence that "chemo brain" and similar cognitive difficulties are the result of cancer treatment toxicity – the researchers excluded those patients who had depression. They were also careful in taking into account what kind of cancer treatments the patients had, and whether or not their cognitive complaints could be due to menopause and its associated hormonal changes. The researchers also used a control group of similarly-aged healthy women who did not have breast cancer.
Dr. Ganz and her colleagues then gave the participants in the study a questionnaire to complete. The researchers found that those who had breast cancer reported more severe complaints than normal, with 23.3 percent of them reporting more severe problems with their memory, and 19 percent reporting severe problems with upper-level cognitive functioning, such as problem-solving and reasoning. It is particularly noteworthy that the patients who reported more severe problems with memory and upper-level cognitive functioning, were those who were more likely to have undergone both chemotherapy and radiation.
Although previous studies have not identified a consistent link between cognitive complaints and neuropsychological testing abnormalities, the UCLA research team found that even when patients complained of only subtle changes in cognitive functioning, neuropsychological testing was able to pick up on those detectible differences.
Specifically, the researchers found that poorer performance on the neuropsychological test was directly linked to those who had more complaints about cognitive functioning, especially if they also had a combination of chemotherapy and radiation treatment, as well as depressive symptoms.
"In the past, many researchers said that we can't rely on patients' self-reported complaints or that they are just depressed, because previous studies could not find this association between neuropsychological testing and cognitive complaints," Ganz said. "In this study, we were able to look at specific components of the cognitive complaints and found they were associated with relevant neuropsychological function test abnormalities."
The researcher team’s findings are part of an ongoing study that will also examine the extent to which hormone therapy contributes to cognitive difficulties, such as poor memory and depression, in breast cancer survivors, as well as how this pre-hormone therapy assessment was able to separate the effects of initial treatments on such difficulties. Earlier post-treatment studies of breast cancer patients included women who were already on hormone therapy; thus, making the findings more difficult to interpret and therefore less certain.
"As we provide additional reports on the follow-up testing in these women, we will track their recovery from treatment, as well as determine whether hormone therapy contributes to worsening complaints over time," Ganz said.
This research was supported by the National Cancer Institute and the Breast Cancer Research Foundation, and by funding from the National Institutes of Health to the Cousins Center for Psychoneuroimmunology.
Source: Patricia Ganz et al. Relating Neuropsychological Test Performance To Cognitive Complaints After Breast Cancer. Journal of the National Cancer Institute, 2013 DOI: 10.1093/jnci/djt112