Cancer, Chemo May Lower Alzheimer's Risk: Study
Results, if confirmed, might point to new treatments
All the patients were over 65 and dementia-free when they first sought medical attention.
On average the veterans were tracked for just shy of six years, during which time more than 82,000 were diagnosed with Alzheimer's. About one-quarter of these patients also had one of 19 different types of cancer. However, roughly three-quarters did not.
Although not all cancers were associated with lower Alzheimer's risk, many were. Having liver cancer was linked to a 51 percent drop in Alzheimer's risk, while pancreatic cancer was linked to a 44 percent drop. Esophageal cancer, myeloma, lung cancer and leukemia were also associated with a lower risk for Alzheimer's, in the range of 33 percent to 23 percent. What's more, such risk reduction could not be explained by the premature death of cancer patients, the study authors said.
However, melanoma, prostate cancer and colorectal cancers were not found to have any protective relationship regarding Alzheimer's risk. Nor was cancer generally linked to a reduced risk for developing other common age-related health complications.
Indeed, cancer patients appeared more likely to experience stroke, osteoarthritis or eye problems, such as cataracts. The majority of cancer patients also appeared to face a higher risk for forms of dementia other than Alzheimer's.
In terms of cancer treatments, undergoing radiation was not linked to reduced Alzheimer's risk. But undergoing chemotherapy lined up with a drop in Alzheimer's risk ranging from 20 percent to 45 percent.
Frain said the research team is now investigating which chemotherapy drugs are associated with a lower risk of Alzheimer's disease.
"The benefit of investigating this unusual, inverse relationship between cancer and [Alzheimer's] may be a better understanding of both diseases and, importantly, the chance to find novel therapies, if drugs can be designed to specifically target one disease without increasing the risk of the other," Frain said.
The study was hailed by Dr. James Galvin, a professor of neurology, psychiatry, nursing and nutrition at NYU Langone School of Medicine in New York City.
"These findings are very important in light of recent studies of mouse models of [Alzheimer's] that showed possibly significant treatment effects on [Alzheimer's] pathology by a number of chemotherapeutic drugs, particularly those used to treat blood-related cancers [and] lung and liver cancers," Galvin said.