Older Patients Who Survive Breast Cancer at Higher Risk for Dementia

The risk for dementia is higher among older patients who are survivors of breast cancer, compared with those without a history of cancer, according to study findings published in the journal Neurology Clinical Practice.

In recent years, the cancer mortality rate has improved, leading to a greater aging population of individuals with cancer. Some studies have shown that older cancer survivors are at a greater risk for age-related conditions; however, the research in this area is limited. Researchers conducted a study to assess the risk for Alzheimer disease (AD), all-cause dementia, and vascular dementia in breast cancer survivors, compared with individuals without a cancer history.

The researchers collected data from the Swedish Total Population Register (TPR) from 1991 through 2015. Study participants were women aged 50 and older diagnosed with breast cancer for at least 5 years. All patients were free of dementia at baseline. 

The researchers followed up with this study cohort for 15 years or until emigration, death, or end of follow-up. A total of 26,741 breast cancer survivors and 249,540 comparison participants were identified from the database. 

International Classification of Diseases (ICD) codes, ninth and tenth revision (ICD-9 and ICD-10) were used for the dementia diagnosis. Dementia was defined by a diagnosis of all-cause dementia, AD, and vascular dementia. 

There was no significant difference in all-cause dementia between breast cancer survivors (incidence rate [IR], 0.12; 95% CI, 0.11-0.14) and individuals without breast cancer (IR, 0.12; 95% CI, 0.12-0.13). For AD and vascular dementia, there were no overall differences in IRs between breast cancer survivors and participants without breast cancer. 

However, when stratifying by age at cancer diagnosis, the researchers found that women aged 65 and older had an increased risk for all-cause dementia (subdistribution hazard ratio [SHR], 1.30; 95% CI, 1.07-1.58), AD (SHR, 1.35; 95% CI, 1.05-1.75), and vascular dementia (SHR, 1.64; 95% CI, 1.11-2.43).

“The methodological differences and definition of cancer survivor are likely the source of these differing results,” the researchers stated. “However, understanding the long-term health risks, including dementia risk, and aging trajectories of the rapidly growing older cancer survivor population will be critical to provide adequate care to these individuals.”

Study limitations included potential inaccuracies in dementia onset date, inability to collect data on race and ethnicity, and lack of generalizability to men with breast cancer.