TUESDAY, Nov. 2 (HealthDay News) -- Researchers report that
drugs used to treat diabetes may indeed both prevent and contain
The findings, being presented Tuesday at the annual meeting of
the American College of Chest Physicians in Vancouver, back up
preliminary data that some diabetes medications might protect
against tobacco-induced lung cancer.
"Patients who did not develop lung cancer had a much higher chance of taking one of these medications than those who did develop lung cancer," said study author Dr. Peter Mazzone. "And those who did develop lung cancer were much less likely to have seen that cancer spread outside the chest and more likely to survive longer with one of these drugs."
Both metformin and the class of drugs known as
thiazolidinediones (which includes Avandia and Actos) are used by
tens of millions of Americans.
A mouse study published in September found that metformin was
associated with up to a 73 percent reduction in the number of
tumors mice developed when they were given a common carcinogen
found in tobacco. The mice had been genetically engineered to be
susceptible to this kind of tumor. Epidemiological studies in
humans have found similar effects.
Metformin was originally marketed as Glucophage, but is now
available as an inexpensive generic.
For this study, Mazzone and his colleagues reviewed and compared
electronic medical records on 225 diabetics with lung cancer with a
similar number of diabetic patients who did not have lung cancer,
although both groups shared other risk factors such as age, smoking
history and gender.
"Forty-one percent of those with lung cancer had taken one of these medications at some point prior to developing the cancer, and 96 percent of all the controls had taken one of these medications in diabetic treatment," reported Mazzone, director of the lung cancer program at The Respiratory Institute at the Cleveland Clinic in Ohio.
Of those with lung cancer, 25 percent of those who developed
metastatic disease (which is disease that has spread) were taking
one of the medications versus 48 percent of those who did not take
one of the drugs.
Also, "the longer someone took the medication, the more
protective it seemed to have been," Mazzone said. "This also
supports the premise that these medications might be able to serve
as risk modifiers."
But there's a long way to go before doctors can start
recommending metformin, Avandia or Actos for otherwise healthy
people to protect against lung cancer.
"There have been no direct studies using these medications in humans for the purpose of preventing or altering the course of lung cancer," Mazzone said. "We need to fully understand the mechanisms by which these medications might prevent or change the course of cancer. We need to develop large clinical trials using these medications and following people forward to see if they are protective, as retrospective studies have suggested."
And the safety profile of these drugs or similar compounds need
to be investigated if the drugs are going to be used in
non-diabetics, he said. For instance, both Avandia and Actos have
been shown to raise the chances of developing certain
cardiovascular risk factors.
"This is the sort of study that raises an interesting question that maybe there is some activity," added Dr. Lucas Wong, an associate professor of internal medicine at Texas A&M Health Science Center College of Medicine, co-director of the Gastrointestinal Cancer Program and principal investigator of the Community Clinical Oncology Program at Scott & White in Temple, Texas. "The harder thing is to figure out how to dose the medication, how to use, [but] just because you're a diabetic and you're taking this medication doesn't mean you're not going to get lung cancer."
It should be noted that research presented at meetings is not
subject to the same scrutiny as peer-reviewed research published in
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