Cancer Survivors Might Have a Decreased Risk for Alzheimer's Disease
The results from a large cohort study of 3.5 million veterans in the Veterans Affairs (VA) Boston Healthcare System show that most types of cancer were associated with a reduced risk of developing Alzheimer’s disease of between 9% and 51%. The cancers associated with the greatest reduction in Alzheimer’s disease risk were liver cancer (51%), pancreatic cancer (44%), esophageal cancer (33%), multiple myeloma (26%), lung cancer (25%), and leukemia (23%). Cancers that did not appear to reduce risk for Alzheimer’s disease or that were linked to increasing risk included melanoma, prostate cancer, and colorectal cancer. Among veterans with a cancer history, treatment with chemotherapy, but not radiation, reduced Alzheimer’s risk by between 20% and 45%, depending on the cancer type, with the exception of prostate cancer. The findings were presented at the 2013 Alzheimer’s Association International Conference.
Researchers from the VA Boston Healthcare System analyzed the health records of 3,499,378 veterans—98% of them men—age 65 and older from 1996 to 2011 who were free of dementia at baseline. The purpose of the study was to evaluate the connection between a history of 14 different cancers, cancer treatment, and the subsequent development of Alzheimer’s disease.
Over a median follow-up of 5.65 years, 82,028 veterans were diagnosed with Alzheimer’s disease; 24% of those veterans had been diagnosed with cancer and 76% had no cancer history. Contrary to the findings for cancer and reduced Alzheimer’s disease risk, the study found no corresponding link between cancer history and reduced risk of any other typical age-related outcomes. Instead the researchers found that having a cancer diagnosis was associated with an increased risk of stroke, osteoarthritis, cataracts, and macular degeneration. And most cancer survivors in the study were also at an increased risk of developing non-Alzheimer’s dementia.
Potential Protective Effect of Cancer on Alzheimer’s
Exactly what role cancer and chemotherapy may have in lowering the risk for Alzheimer’s disease and in providing potential therapeutic possibilities for the disease is unclear and needs further study, concluded the researchers.
“The potential protective effect of chemotherapy is supported by recent experimental studies,” Laura Frain, MD, a geriatrician at the VA Boston Healthcare System and a co-researcher on the study, said in a statement. “The results of this study are interesting because they could help focus future research onto the specific pathways and treatment agents involved in the individual cancers that are associated with a reduced risk of Alzheimer’s. This could potentially open new therapeutic strategies for Alzheimer’s prevention and treatment.”
The study was funded by a Veterans Affairs Career Development Award. The authors have disclosed no relevant financial relationships.
The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.
