MONDAY, July 15 (HealthDay News) -- If battling a deadly disease
can be said to have a silver lining, this might be it: Many forms
of cancer appear to lower the risk for developing Alzheimer's
disease, new research suggests.
After sifting through the health records of nearly 3.5 million
patients, investigators concluded that most kinds of cancer seem to
confer some degree of protection against Alzheimer's, reducing risk
of the age-related brain disorder by anywhere from 9 percent to 51
And they have also linked a common form of cancer treatment --
chemotherapy -- to a lower risk for developing Alzheimer's-related
"We found that the majority of cancers were associated with a decreased risk of [Alzheimer's disease]," said study lead author Dr. Laura Frain, a geriatrician with the VA Boston Healthcare System. "This does not mean that if you have cancer you won't get [Alzheimer's], but that you may have a decreased risk, depending on the cancer type."
Chemotherapy conferred additional protection against Alzheimer's
in most cancers, with the exception of prostate cancers, Frain
said. "Our findings suggest that some chemotherapies may have a
neuroprotective action. Further studies are needed to confirm
this," she added.
Frain and colleagues are scheduled to present their findings
Tuesday at the Alzheimer's Association international conference in
Boston. The research uncovered an association between some cancers
and possible protection from Alzheimer's, but it did not prove the
existence of a cause-and-effect relationship.
Frain's findings come on the heels of another large study
published online July 10 in
Neurology, in which an Italian team also unearthed a
potential protective link between cancer and Alzheimer's
In that case, investigators identified an inverse relationship
between cancer and Alzheimer's disease, in which having cancer
appeared to lower the risk for Alzheimer's by 35 percent, while
having the progressive brain disease lowered the risk for cancer by
For the current effort, Frain's team pored through the medical
paperwork of millions of American veterans who moved through the VA
health care systems between 1996 and 2011.
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
Frain said the research team is now investigating which
chemotherapy drugs are associated with a lower risk of Alzheimer's
"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.
Dr. Catherine Roe, an instructor in neurology at Washington
University School of Medicine in St. Louis, seconded the
"If other scientists also find that chemotherapy is associated with a reduced risk of Alzheimer's disease, then it would be a good sign that we may be able to come up with a treatment that is effective in preventing Alzheimer's disease in the future," she said.
The data and conclusions of research presented at meetings
should be considered preliminary until published in a peer-reviewed
For more on Alzheimer's, visit the
U.S. National Institutes of Health.
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