Breast Cancer Survivors May Face Lower Alzheimer Disease Risk

Breast cancer survivors had a slightly lower risk of Alzheimer disease (AD) compared with women without breast cancer, particularly among older survivors and those treated with radiation therapy. The findings of a large, population-based study conducted in South Korea published in JAMA Network Open suggest that certain cancer treatments may be associated with a potential protective effect against AD contrary to concerns of cancer-related cognitive impairment heightening long-term dementia risk.

The findings result from a retrospective cohort analysis of data from the Korean National Health Insurance Service database, which includes health claims and national screening data. The study cohort included 70,701 women who underwent breast cancer surgery between 2010 and 2016, matched 1:3 with 180,360 cancer-free participants as controls. Researchers assessed participant data to determine risk of AD among both groups, which was defined using records of International Classification of Diseases (ICD-10) diagnostic codes and prescriptions for anti-dementia medications. Participants received follow-up for a median 7.3 years.

Breast cancer survivors had an 8% lower risk of AD compared with controls:

• There were 1229 cases of AD among breast cancer survivors (2.45 per 1000 person-years) vs 3430 cases among controls (2.63 per 1000 person years), with an adjusted subdistribution hazard ratio (SHR) of 0.92 for breast cancer suvivors vs controls (95% CI, 0.86 to 0.98).
• For women aged ≥65 years, the risk reduction for AD was more pronounced (SHR, 0.95; 95% CI, 0.85 to 0.99) than for younger age groups.
• The lower risk associated with breast cancer survivorship was not found to extend beyond 5 years of survival.
• Radiation therapy was associated with a reduced risk of AD among survivors (adjusted hazard ratio [HR], 0.77; 95% CI, 0.68 to 0.87).