October 22, 2018 – The first large U.S. study of cognition in older breast cancer patients found that most women don’t experience cancer-related cognitive problems within the first two years after diagnosis and treatment.
But researchers also observed a troubling trend involving chemotherapy and a specific gene found to increase the risk of Alzheimer’s disease.
Though further exploration is needed, the small subset in the study of women experiencing cognitive decline were unique in having that gene, and the effect was most pronounced after chemotherapy treatment.
The research, recently published in the Journal of Clinical Oncology, is part of the ongoing Thinking and Living with Cancer study led by Georgetown’s Dr. Jeanne Mandleblatt.
Effects of Treatment
The results of the study, which compared hundreds of breast cancer patients ages 60 to 98 before and after treatment to a group of same age cancer-free women, “are good news for the majority of breast cancer patients who worry about potential long-lasting cognitive effects of treatment,” says Mandelblatt, professor of oncology at Georgetown Lombardi Comprehensive Cancer Center.
“Our study suggests that for most older breast cancer patients, chemotherapy and hormonal treatments do not have major adverse effects on cognitive function, at least as measured by our current tests,” she says.
Impact of Genotype
Mandelblatt says patients more likely to have cognitive issues were a small group who have one or two copies of the gene, APOE4, but the data are inconclusive and will be examined more thoroughly.
Researchers found that these patients tended to show a steady decline in cognitive function test scores after chemotherapy compared to APOE4-negative patients and non-cancer participants.
“It is not that the chemotherapy causes Alzheimer’s disease, but that these patients may be at risk for both cancer-related cognitive problems and Alzheimer’s perhaps through a process of accelerated aging or other shared disease processes,” Mandelblatt says.
She adds that the apparent interaction of APOE4 and breast cancer chemotherapy will be of interest to the many scientists who research the basis of neurodegeneration.
Discussing Care Options
Mandelblatt stresses that this early finding needs to be verified in additional studies that include more breast cancer patients with the APOE4 gene who are exposed to chemotherapy.
If the findings are replicated and extended, then genotyping could be useful when breast cancer patients discuss treatment options with their oncologists, Mandelblatt says.
“In any case, all patients should discuss any concerns about cognitive issues during and after treatment with their care team,” she adds.