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 Earlier studies had suggested that aspirin and non-steroidal
anti-inflammatory drugs (NSAIDs) such as ibuprofen may help protect
against colorectal cancer, but it wasn't clear how much had to be
taken, and for how long, to achieve those benefits.
Now, using data on more than 113,000 individuals, researchers have
been trying to sort out the relationship between aspirin and NSAIDs,
duration of treatment, and colorectal cancer rates.
In general, the risk of developing colorectal cancer varies with
age, race, ethnicity and lifestyle. More than 90 percent of cases
are diagnosed in people older than 50, according to the National
Cancer Institute.
An online risk calculator from the Centers for Disease Control and
Prevention (available here: http://1.usa.gov/1DlscTL) indicates that
in the U.S., for an average white or black woman in her late
fifties, the 10-year risk of developing colorectal cancer is between
1 and 1.4 percent, and her lifetime risk is between 5 and 5.4
percent. For an average black or white male of the same age, the
corresponding risks would be about 1.4 percent and 5.8 percent.
In the new study from Denmark, taking low-dose aspirin continuously
for at least five years appeared to reduce the risk of colorectal
cancer by 27%, and using nonaspirin NSAIDs for at least five years
appeared to reduce it by 30%.
On the other hand, merely having taken aspirin did not alter the
colorectal cancer risk, they reported in Annals of Internal
Medicine.
“Unless low-dose aspirin is taken continuously, there is little
protection against colorectal cancer,” Dr. Soren Friis from the
Danish Cancer Society Research Center in Copenhagen told Reuters
Health.
Nonaspirin NSAIDs were also protective against colorectal cancer
with consistent long-term use, "and there was some indication that
even non-continuous use of these agents may be (marginally)
effective for the prevention of colorectal cancer,” Dr. Friis said.
Aspirin and NSAIDs carry their own risks, however. Long-term use can
cause gastrointestinal bleeding, for example, so the potential
reduction in colon cancer risk needs to be balanced against
potential side effects, the authors warn.
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The study had several limitations. For instance, the researchers
only had data for users who obtained their aspirin or NSAIDs from
doctors’ prescriptions. They didn’t include patients who made
over-the-counter purchases of the medicines. Also, the researchers
can’t rule out the possibility that other factors may have increased
participants’ risk for colorectal cancer, such as obesity, dietary
habits, alcohol use, and family history of colorectal cancer.
Dr. Friis emphasized that people should not start taking aspirin or
NSAIDs on the basis of the new findings.
“Self-medication with aspirin or non-aspirin NSAIDs is strongly
discouraged, due to the possibility of serious adverse events,” Dr.
Friis said. “The public should not take any medication regularly
without consulting with a physician.”
Dr. Gurpreet Singh Ranger from Upper River Valley Hospital,
Waterville, New Brunswick and Dalhousie Medical School, in Halifax,
Nova Scotia, Canada, agreed with Dr. Friis.
“Low dose aspirin, already taken regularly by millions, reduces the
risk of colorectal cancer,” he told Reuters Health by email. But
“before starting to take aspirin long term, it is important to
discuss the implications with your family doctor or specialist.”
SOURCE: http://bit.ly/1i46lF7 Annals of Internal Medicine, online
August 24, 2015.
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