Dogs Smell Signs Of Cancer
Dogs have long been used
to sniff out explosives, narcotics, and even counterfeit currency.
Now, a new study shows that man's best friend can also detect
lung and breast cancer in breath samples.
"When we heard anecdotally that there was a device out there
that might be able to detect cancer at its earliest stages, before
it even shows up on an MRI [magnetic resonance imaging], it was
something we wanted to pursue," said Nicholas Broffman, executive
director of the Pine Street Foundation, a nonprofit group in
California that conducted the study. The group helps cancer patients
who are facing tough treatment decisions.
That device, of course, is a dog, and researchers believe it
picks up on chemical differences that linger in the breath of
a person with cancer.
While canines won't ever replace standard medical testing, experts
think they may become an important early screening tool in the
In this study, three Labrador retrievers and two Portuguese
water dogs were trained in three weeks to either sit or lay down
in front of breath samples from lung and breast cancer patients,
while ignoring those of healthy individuals.
"These were not super dogs," said Broffman. "They were just
ordinary household pets."
The trial comprised of breath samples from 55 patients with
lung cancer, 31 with breast cancer, and 83 healthy people. The
samples were captured in special tubes.
All cancer patients had recently been diagnosed through conventional
methods, such as mammograms or CT scans, but had not yet begun
chemotherapy. And the trial samples were different from the ones
used to train the dogs.
The results show the dogs were 88 percent to 97 percent accurate
in identifying both early- and late-stage breast and lung cancers.
The study will appear in the March issue of Integrative
Cancer Therapies .
Catching cancer early increases survival
rates and allows for treatment with lower toxicity, experts
The ability of dogs to detect cancer was first discovered in
1989, and reported in the medical journal The Lancet .
A woman's pet had alerted her to the presence of melanoma by
constantly sniffing the skin lesion on her leg. Subsequent studies
have shown dogs can smell melanoma and bladder cancer.
"I think all of these [studies and observations] are saying
this ought to be looked at more carefully and ought to be taken
seriously," said James Walker, director of Florida State University's
Sensory Research Institute in Tallahassee.
He says a dog's nose is so powerful it can detect odors 10,000
to 100,000 times better than a human nose can.
Later this year, he plans to launch a study on canine detection
of bladder cancer.
Veterinarian Larry Myers, from Auburn University in Alabama,
is currently working on four canine-cancer detection projects.
He said he has some doubts, though, about the Pine Street study.
"What makes me a little curious about this is they are talking
about three weeks of training for these dogs and getting [a high]
percent of accuracy," Myers said.
In the past, Myers has trained dogs to find everything from
drugs to off-flavored catfish, but it usually takes him five
to six weeks. The U.S. military, he pointed out, spends about
three months training explosive detection dogs.
Regardless of training differences, Myers thinks dogs could
be used five to 10 years from now to screen for cancer at local
health fairs or in Third World countries.
In the meantime, though, more research has to be done.
"Everybody needs to be careful and not overstate how wonderful
these [studies] are," said Myers. "We need to approach [this
type of research] slowly, cautiously and scientifically."
For more on dogs and their cancer-detecting abilities, go to Sensory
Research Institute .
SOURCES: Nicholas Broffman, executive director, Pine Street
Foundation, San Anselmo, Calif.; James Walker, Ph.D., director,
Sensory Research Institute, Florida State University, Tallahassee;
Larry Myers, associate professor, Auburn University College of
Veterinary Medicine, Auburn, Ala.; March 2006 Integrative
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