Breast cancer survivors report substantially more cognitive difficulties as much as 6 months after chemotherapy compared with age-matched controls, according to new research.
The result, from a study of 581 breast cancer patients recruited from community practices across the United States, adds to evidence from other studies which show that cognitive difficulties after chemotherapy, colloquially known as chemofog or chemo brain, are a real problem for breast cancer survivors, the authors write.
"One of the main goals of our study, which was the largest prospective, longitudinal study in the community to date, was to help us understand more about the cognitive complaints that patients often report during their cancer treatments and to better understand the trajectory of those cognitive problems," lead author Michelle C. Janelsins, PhD, from the James P. Wilmot Cancer Institute, University of Rochester Medical Center, New York, told Medscape Medical News.
"We found that a significant percentage of our breast cancer patients, 45.2%, reported that they had clinically meaningful changes in their cognitive function from before treatment to after treatment, compared with only 10% of healthy controls," Dr Janelsins said.
"That's a lot of people who are complaining of problems. And after 6 months, although there was some rebound, still 36.5% of breast cancer patients were complaining of problems with cognitive function, compared with 13.6% in the control group," she added.
The study was published in the February issue of the Journal of Clinical Oncology.
For the study, 581 patients with breast cancer and 364 age-matched noncancer controls completed the Functional Assessment of Cancer Therapy — Cognitive Function (FACT-Cog) before and after chemotherapy, and again 6 months after the course of chemotherapy had ended.
Controls were family members, friends of patients, or unrelated, and obtained from the National Cancer Institute Community Oncology Research Program (NCORP) research database, Dr Janelsins explained.
"The FACT-Cog is a validated measure of patient-reported outcomes that was developed specifically to assess cognitive challenges identified by patients with cancer," she noted.
The mean age of study participants was 53 years, and 48% of breast cancer patients received anthracycline-based chemotherapy regimens.
Before any chemotherapy, FACT-Cog scores were lower in patients with breast cancer compared with controls (P < .001). Older age (P = .009), black race (P = 0.34), lower reading ability, higher anxiety, and higher depressive symptoms (all P < .001) were predictive of lower FACT-Cog scores at baseline. Education, however, was not predictive (P = .809).
Significantly greater cognitive complaints, as shown by declines in the FACT-Cog score as well as four subscales (perceived cognitive impairment [PCI], perceived cognitive abilities [PCA], and impact on quality of life [QOL]), were reported by breast cancer patients compared with controls before, immediately after, and 6 months after chemotherapy (P < .001) at all time points.
This study has several strengths, Patricia A. Ganz, MD, professor of medicine and public health at UCLA Schools of Medicine and Public Health, Los Angeles, California, told Medscape Medical News.
In addition to its large sample size and control group, the use of self-reported perceptions of cognitive decline could also be considered a strength, commented Dr Ganz, who coauthored an accompanying editorial.
"This is a large trial, where they also did neuropsychological testing, although those results were not reported in this paper," Dr Ganz said.
"The issue is, how much does self-reported difficulty with cognition relate to test-associated changes? The tests, by and large, that are used in these settings are pretty crude in the sense that they are designed to pick up big changes, whereas these patients may have much more subtle changes, and as a result, self-report may actually be more sensitive at detecting these changes," she said.
"For instance, the neuropsychologist will tell you that you have to have more than a one or two standard deviation difference to say somebody is impaired, but I think what patients are really aware of is that they can perceive a difference. It's just not big enough in magnitude to be detected on these tests," Dr Ganz said.
"The other thing that we find is that the norms for a lot of these tests are based on the general population who have an IQ of 100, whereas at least in the breast cancer patients we have tested, some have IQs of 110, 120, so they are brighter and may still appear in the normal range, but they are not perceiving their mental functioning as being normal," she said.
Both Dr Janelsins and Dr Ganz agree that the findings from this and other studies should reassure breast cancer survivors who experience symptoms of cognitive impairment after chemotherapy that what they are experiencing is, indeed, real.
"This is one of the largest studies to be conducted to date in a nationwide setting and is really validating concerns that patients have — that this is a real problem and it needs respect. Patients should be aware this is a possible side effect of cancer treatment, and if they are having any concerns about their cognition they should bring them up with their provider and not just brush them off as an aging effect. These are real problems," Dr Janelsins emphasized.
The study results reinforce the perception that something is going on with these women, Dr Ganz agreed.
"Women will come in and say 'I can't think straight,' or 'It's really hard for me to concentrate,' or 'I'm having trouble finding words. I used to be able to start to work at my computer and I'd know what I was doing, but now I forget within a few minutes why I am sitting there,'" she said.
"Those are the kinds of things patients who have had cancer treatments often complain of. Many patients are able to go back to work, but continued to be troubled by these problems, but others are unable to. I remember one patient who was legal counsel for a big corporation. She just couldn't go back to work," Dr Ganz said.
The study was supported by the National Cancer Institute. Dr Janelsins has reported no relevant financial relationships. Dr Ganz has reported financial relationships with Intrinsic LifeSciences, Xenon Pharma, Silarus Therapeutics, Merganser Biotech, Teva Pharmaceuticals, Novartis, Merck, Johnson & Johnson, Pfizer, GlaxoSmithKline, Abbott Laboratories, Keryx Biopharmaceuticals, InformedDNA, and Vifor Pharma.