Many patients undergoing cancer treatment are worried about cognitive decline leading to dementia. Domestic medical professionals revealed that such concerns are unnecessary. In fact, the risk of developing dementia for breast cancer patients receiving chemotherapy and radiotherapy was found to be lower than that of the general population.
Samsung Medical Center stated on the 18th that a joint research team consisting of Professor Shin Dong-uk from the Department of Family Medicine and Professor Han Kyung-do from the Department of Statistics and Actuarial Science at Soongsil University, along with Professor Jung Soo-min from Seoul National University Hospital, presented the results of a study analyzing the risk of Alzheimer's dementia in breast cancer patients published in the journal "JAMA Network."
Alzheimer's disease is a disorder characterized by the accumulation of abnormal proteins inside and outside nerve cells, damaging them and impairing cognitive abilities such as memory and learning. While a treatment that reduces abnormal proteins has emerged to delay dementia effects, side effects such as brain swelling or bleeding are considered limitations.
The research team compared 70,701 patients who underwent surgery for breast cancer between 2010 and 2016 with 180,360 individuals who did not have cancer. The team selected general individuals based on the age and other conditions of breast cancer patients.
As a result of a 7.9-year follow-up observation, the number of dementia diagnoses per 1,000 person-years was recorded as 2.45 cases in the breast cancer surgery patient group, while the control group had 2.63 cases. Person-years refer to the total observation time for multiple individuals. In simpler terms, this means that when observing 1,000 individuals in both the breast cancer patient group and the control group for one year, 2.45 breast cancer patients and 2.63 general individuals were diagnosed with dementia.
After considering dementia-related risk factors such as age, gender, income level, residence, obesity, diseases, smoking, drinking, and activity levels, the research team found that the risk of developing dementia was 8% lower for breast cancer patients compared to the general population. Notably, patients who received radiotherapy showed a reduction in dementia risk by approximately 23% compared to the general population.
The research team analyzed that this was the result of multiple principles working in conjunction. They stated that medications commonly used in breast cancer treatment may temporarily lower patients' attention and concentration, but there is no evidence indicating a long-term correlation with dementia.
On the other hand, it was suggested that anthracycline drugs may have a protective effect against dementia by preventing the accumulation of dementia-causing substances like tau proteins or by removing those that have already accumulated. In fact, a joint research group from the Gladstone Institutes in the U.S. and the University of California, San Francisco (UCSF) announced on the 22nd of last month in the journal "Cell" that the breast cancer medication "letrozole" and the colorectal cancer and lung cancer medication "irinotecan" are effective in treating Alzheimer's disease.
Professor Jung Soo-min from Seoul National University Hospital noted, "There are patients who experience temporary cognitive decline during the breast cancer treatment process, but this study confirmed that such cognitive decline is not associated with long-term dementia risk," adding that, "We need to focus on recovery and maintaining health rather than anxiety about treatment."
Professor Shin Dong-uk from Samsung Medical Center said, "Breast cancer patients need to pay more attention to other risk factors." For the same breast cancer patients, the risk of developing dementia increases 2.04 times for smokers, 1.58 times for those with diabetes, and up to 3.11 times for patients with chronic kidney disease.
References
JAMA Network (2025) DOI: https://10.1001/jamanetworkopen.2025.16468
Cell (2025), DOI: https://doi.org/10.1016/j.cell.2025.06.035