Retrospective cohort study of Alzheimer disease and related dementia following hormone-modulating therapy for hormone receptor-positive breast cancer

Hormone-modulating therapy (HMT) is an accepted treatment for hormone receptor-positive breast cancer. The cognitive effects of this treatment, including a potential link to Alzheimer disease and related dementia (ADRD), are understudied. A retrospective cohort study using the SEER-Medicare database identified 18,808 women aged 65 years or older with a diagnosis HR-positive breast cancer between 2007 and 2009. Among these women, 65.7% received HMT within 3 years of diagnosis, while 34.4% did not. During an average 12 years of follow-up, 23.7% of HMT users and 27.9% of non-HMT users developed ADRD. HMT was associated with a 7% lower risk of ADRD overall (HR 0.93; p=0.005). The reduction of ADRD risk with HMT use decreased with increasing age and varied by race. Women aged 65 to 74 years who self-identified as Black experienced a 24% relative risk reduction compared with an 11% relative risk reduction in White patients. These associations diminished at age 75 years or older in White women but persisted in Black women. The authors conclude that these results suggest that the association of HMT and ADRD varies by age and race; when deciding on breast cancer treatment, therapy and individual factors must be considered.