Breast Cancer Survival Linked to Lower Alzheimer's Risk, Study Finds

A recent study conducted by researchers at Samsung Medical Center reveals that breast cancer survivors have an 8% lower risk of developing Alzheimer's disease (AD) compared to individuals without a cancer history. This significant finding, published in JAMA Network Open on June 24, 2025, highlights the potential short-term protective effects of radiation therapy against Alzheimer's, particularly among older survivors.

Breast cancer, which affects over 2.3 million women globally each year, is the most prevalent cancer among women, with survival rates exceeding 93% for early-stage diagnosis. As more women live longer after treatment, the focus on the long-term cognitive effects of breast cancer therapies has intensified. Survivors often report cognitive issues, collectively termed cancer-related cognitive impairment or 'chemobrain,' leading to questions about the relationship between breast cancer survivorship and dementia risk.

In the study titled "Alzheimer Disease in Breast Cancer Survivors," researchers utilized national health insurance data to analyze AD incidence among 70,701 breast cancer survivors who underwent surgery between 2010 and 2016. These individuals were matched with 180,360 cancer-free controls, with all participants monitored for an average of 7.3 years. The incidence of AD was measured through clinical diagnoses confirmed by prescribed dementia medications.

The results indicated that breast cancer survivors experienced a lower incidence rate of Alzheimer's, with 2.45 cases per 1,000 person-years compared to 2.63 cases per 1,000 in the control group. Notably, survivors aged 65 or older exhibited a significantly reduced risk. However, the protective effect of breast cancer survivorship appeared to diminish over time, becoming indistinguishable from controls after five years, suggesting a limited window of reduced risk associated with the timing of treatment.

Among various treatments studied, radiation therapy emerged as significantly correlated with a reduced risk of Alzheimer's, with an adjusted hazard ratio (AHR) of 0.77, indicating a 23% lower risk of developing AD. In contrast, other treatments such as anthracycline chemotherapy and endocrine therapies did not show statistically significant associations with Alzheimer's risk.

The researchers conclude that while breast cancer survivors generally benefit from a modestly reduced short-term risk of Alzheimer's—particularly following radiation therapy—this effect is not permanent. The findings prompt a call for enhanced Alzheimer's surveillance among cancer survivors and suggest the integration of dementia risk management into survivorship care plans.

As life expectancy continues to grow among breast cancer survivors, understanding the interplay between cancer treatments and cognitive health remains crucial. Future research may focus on the biological mechanisms behind these observations and explore the long-term cognitive health implications for this growing population of survivors. This study serves as a pivotal step in contextualizing the broader impacts of cancer treatment on cognitive health, highlighting the need for ongoing support and tailored care strategies for individuals navigating survivorship.