In a cohort study, hormone-modulating therapy (HMT) for breast cancer treatment was associated with a lower risk of Alzheimer's disease and related dementias in women aged 65 years and older, with differences observed by age and race.
Published in JAMA Network Open, the study analyzed data from 18,808 women newly diagnosed with breast cancer between 2007 and 2009 using the Surveillance, Epidemiology, and End Results-Medicare linked database. The researchers used propensity score weighting to balance treatment groups on baseline characteristics. Competing risk and immortal time bias were addressed in the analyses.
Over an average 12-year follow-up period, 23.7% of the 12,356 HMT users and 27.9% of the 6,452 non-HMT users developed Alzheimer's disease or related dementias. HMT was associated with a statistically significant 7% relative risk reduction in Alzheimer's disease or related dementias (hazard ratio [HR], 0.93; 95% confidence interval [CI], 0.88-0.98; P=.005).
The risk reduction was most pronounced in women aged 65 to 74 years, especially among those who self-identified as Black (HR, 0.76; 95% CI, 0.62-0.92). For Black women, the association persisted but attenuated after age 75 (HR, 0.81; 95% CI, 0.67-0.98). White women aged 65 to 74 had an 11% relative risk reduction with HMT (HR, 0.89; 95% CI, 0.81-0.97), which was not significant after age 75. No significant association was seen for women of other races.
Aromatase inhibitors and selective estrogen receptor modulators showed significant risk reductions for Alzheimer's disease or related dementias compared to receipt of no HMT in this patient population.
The authors noted some study limitations, including lack of genetic data, inability to assess HMT duration beyond 3 years, and potential residual confounding. They emphasized the need for considering individual factors when deciding on breast cancer treatment.
Conflict of interest disclosures available in the study.