Breast Cancer Treatment May Protect Against Dementia

Some breast cancer survivors may be protected from dementias after receiving select hormone therapies, research found.

Hormone-modulating therapy (HMT), which is used to treat breast cancer, may decrease patients’ risk of Alzheimer’s disease and other forms of dementia, according to research published in JAMA Network Open.

HMTs, such as Faslodex (fulvestrant), Orserdu (elacestrant) and Femara (letrozole) are used to treat cancers that are affected by hormones estrogen and progesterone, according to the American Cancer Society. Prior research has shown mixed results on whether HMTs increase or decrease the risk of dementias.

“Our study suggests that younger women may benefit more from HMT in terms of reduced risk of developing Alzheimer’s disease and other types of dementia,” study author Chao Cai said in a press release about the findings.

Cai is an assistant professor at the University of South Carolina College of Pharmacy. She and colleagues analyzed data from a federal database of women aged 65 and older who were diagnosed with breast cancer between 2007 and 2009 and had no prior history of HMT or dementias before their breast cancer diagnosis.

A total of 18,808 patients were studied, and 66% had HMT within three years of diagnosis. Among this group treated with HMT, 24% developed Alzheimer’s disease and related dementias within an average of 12 years follow-up. In the same time frame, 28% of those who did not use HMTs developed a dementia.

The researchers found that HMT’s protective effect against Alzheimer’s disease and other dementias was most prominent in women between the ages of 65 through 69. The protective effect decreased as the patients got older, and in patients over the age of 80, HMT use led to an increase in dementias.

“The benefits of HMT decreased for women aged 75 and older, particularly in those who identified as white. This suggests that the timing of HMT initiation is crucial and treatment plans should be tailored to a patient’s age,” Cai said.

Additionally, the protective factor tended to be more prominent in Black women compared with White women. Specifically, Black women between the ages of 65 and 74 had a 24% reduction in relative risk of developing a dementia with HMT, while the risk decrease was 11% in White women in the same age group. The risk decrease went down to 19% in Black women over the age of 75 and disappeared in Black women.

“Black women have higher rates of breast cancer and tend to have higher lifetime stress due to structural racism and other societal factors, which are associated with worse outcomes,” said senior author, Francesmary Modugno, a professor of obstetrics, gynecology and reproductive sciences at the University of Pittsburgh said in the release. “We don’t know the mechanisms behind the racial disparities we saw with HMT and risk of [Alzheimer’s disease and related dementias], but it’s possible that these factors could contribute. It deserves further investigation.”

Ultimately, continued research on this topic could better help personalize care, according to the authors.

“The relationship between HMT for breast cancer and dementia risk is complex and influenced by multiple factors,” Cai said. “Ongoing research is needed to further understand the mechanisms behind this association and provide clearer guidance on the use of HMT.”

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