Hormone-modulating therapy decreased risk of dementia in breast cancer patients

1. In a retrospective cohort study of women newly diagnosed with breast cancer, use of hormone therapy was associated with a decreased risk of developing alzheimer’s disease and related dementia (ADRD), especially in Black women and women younger than 75 years old. 

Evidence Rating Level: 2 (Good) 

Breast cancer is one of the most common cancer diagnoses in the United States and is the most common among women. One significant non-modifiable risk factor for developing cancer is age and the majority of breast cancer cases (83%) are found in women 50 years or older. Many new patients are receiving diagnoses of Alzheimer’s Disease (AD) along with an increase in AD and related dementia (ADRD). Since there are more breast cancer survivors, there is a concern about developing ADRD in this population. Some common treatments for breast cancer include chemotherapy, hormone-modulating therapy (HMT), radiation, and surgery. A prospective cohort study was conducted. This prospective cohort study aimed to investigate the association between HMT use and the risk of ADRD in new breast cancer cases. Among 18 808 women who met the inclusion criteria, 12 356 of them (65.7%) were exposed to HMT at some point in the first three years since their diagnosis whereas 6452 (34.3%) had no exposure. Within the population, 2926 (23.7%) and 1802 (27.9%) of HMT and non-HMT users respectively developed ADRD. Death resulted in 3262 (26.4%) patients in the HMT group and 1776 (27.5%) patients in the non-HMT group. The risk of developing ADRD significantly decreased in those taking HMT (HR, 0.93; 95% CI, 0.88-0.98; P=.005). There was a 7% lower relative risk associated with ADRD (HR, 0.93; 95% CI, 0.88-0.98; P=.005). After the first set of analyses, the participants were divided into two groups based on age (65-74 years and ≥75 years) to assess further the relationship between age, race and ADRD risk. Among Black women, those in the age group between 65 to 74 years had a significantly reduced risk of developing ADRD (HR, 0.76; 95% CI, 0.62-0.92). Similarly, among white women, those in the same age group (65-74 years) also had a risk reduction of 11% (HR, 0.89; 95% CI, 0.81-0.97) however there was no association in women 75 years or older (HR, 0.96; 95% CI, 0.90-1.02). In summary, HMT was associated with a risk reduction in developing ADRD among women aged 65 or older who were recently diagnosed with breast cancer. 

Click to read the study in CMAJ

Image: PD

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