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Can Chemo Cause Cognitive Decline in Older Patients?

November 28, 2018

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 By Ann Miller Baker

“Chemobrain” – the foggy feeling that clouds thinking for some cancer patients – is real. A new study that included Moffitt breast cancer patients over age 60 shows it may be more of a risk for those who carry a gene associated with Alzheimer’s disease. But overall, the number of study participants who experienced cancer-related cognitive challenges was reassuringly small.

The research, published recently in the Journal of Clinical Oncology, is part of the Thinking and Living with Cancer (TLC) Study, a multi-center prospective study to evaluate cognitive changes in older cancer patients. Normal aging increases risks for cognitive declines regardless of cancer status. While they are not at higher risk of Alzheimer’s or other forms of dementia than the general population, many cancer patients are concerned about the much more subtle cognitive impacts associated with chemobrain. Yet prior to the TLC Study, little research existed on how cancer treatment impacts those risks for older patients.

Researchers compared cognitive skills testing results of 603 individuals over the age of 60 for a two-year period. Roughly half (281) had been diagnosed with non-metastatic breast cancer. Participating cancer patients were divided into two groups: those treated with chemotherapy with or without hormonal therapy, and those treated with hormonal therapy alone.

The remaining study participants (controls) were women of similar ages and socioeconomic status who had no evidence of cancer. Baseline cognitive testing was done when participants enrolled in the study, and before patients began treatment for breast cancer. Follow-up testing was performed at 12 and 24 months.

The results showed that older patients who received chemo experienced mild declines over time in attention or processing information. No cognitive declines were shown in those treated with hormones alone or in the control group.

All participants were then screened for the presence of a specific version of the APOE gene, which is a known risk factor for late-onset Alzheimer’s disease. Among the cancer patients, 53 were positive for the gene, while 81 were positive among the control group. The decline in cognitive scores was greater for patients with the gene who’d been treated with chemo in the first two years after treatment when compared to the gene-positive controls.

Dr. Heather S. Jim, researcher, Moffitt Health Outcomes and Behavior Program

“Our research shows that older breast cancer survivors with this Alzheimer’s-related gene may be at risk for cognitive decline, especially after chemotherapy,” says co-author and Moffitt researcher Dr. Heather Jim. “This information could help clinicians discuss treatment options when chemotherapy is discretionary because many older cancer survivors are concerned about cognitive problems related to their treatment.”

The TLC study continues to enroll patients and follow existing participants, with the goal of learning more about a possible relationship between chemotherapy, gene status and cognitive decline over at least five years.