Breast Cancer Survivors may have Lower Alzheimer's Risk, Linked to Radiation Therapy: JAMA

A recent Korean study published in the Journal of American Medical Association found that breast cancer survivors had a slightly lower risk of developing Alzheimer's dementia (AD) when compared to cancer-free individuals. The reduced risk was notably associated with radiation therapy, while other treatments showed no significant effect. However, the protective effect was strongest at 6 months post-treatment and diminished over time.

This research evaluated data from over 70,000 breast cancer patients who underwent surgery between 2010 and 2016. These individuals were matched 1:3 with cancer-free controls and followed for a median of 7.3 years. The analysis was completed in the first half of 2024 using data from the Korean National Health Insurance Service.

Over the study period, 1,229 cases of AD were diagnosed among breast cancer survivors, equating to an incidence rate of 2.45 cases per 1,000 person-years. After adjusting for socioeconomic status and comorbidities, this study found that breast cancer survivors had a modestly reduced risk of AD when compared to the control group, with a subdistribution hazard ratio (SHR) of 0.92 (95% CI, 0.86–0.98).

The reduced risk was particularly noticeable among survivors aged 65 years and older (SHR, 0.92; 95% CI, 0.85–0.99). However, a landmark analysis revealed that the lower risk of AD was no longer statistically significant after 5 years of survival, suggesting that the early survivorship period may uniquely influence cognitive outcomes.

Radiation therapy was linked to a notably lower risk of developing AD, with an adjusted hazard ratio (HR) of 0.77 (95% CI, 0.68–0.87). Meanwhile, anthracycline-based chemotherapy, often associated with cognitive complaints, did not significantly increase the risk of AD in this cohort. The findings showed that younger survivors had an overall lower incidence of AD when compared to older groups, and those who received radiation therapy experienced the lowest observed rates of AD.

Overall, this study contributes to the nuanced understanding of “chemo brain” and cognitive aging in cancer survivors. While treatment-related cognitive impairment remains a valid concern, this research suggests that some treatments may offer neuroprotective benefits, possibly through mechanisms related to inflammation, immune modulation, or vascular changes.

Reference:

Jeong, S.-M., Jung, W., Cho, H., Choi, H. L., Jeon, K. H., Nam, K.-W., Lee, Y.-G., Kim, B., Han, K., & Shin, D. W. (2025). Alzheimer disease in breast cancer survivors. JAMA Network Open, 8(6), e2516468. https://doi.org/10.1001/jamanetworkopen.2025.16468