It’s usually complicated and incredibly expensive to develop a
new way to screen for cancer or to diagnose other serious medical
problems -- but not always! I just learned about a promising new
approach to detecting cancer that requires no radiation, no blood
sample and no biopsy... is cost effective and highly accurate...
and furry. Researchers are finding that dogs and other animals can
be highly effective at finding the disease in humans early,
accurately and economically. Moreover, when animals detect a
disease, the procedure is noninvasive.
Several years ago I reported on dogs "smelling" skin cancer.
Since then, the field has expanded in very exciting ways. To find
out more about this research, I contacted two leading scientists in
the field. In speaking with them, I got an inside look at research
that will almost certainly have a major impact on health
care.
THE BREATH TEST
Michael McCulloch, LAc, MPH, PhD, is the head researcher of
the Pine Street Foundation, a cancer research organization in San
Anselmo, California. Dr. McCulloch told me that in one of the
foundation’s recent studies, a group of 86 volunteer patients known
to have breast or lung cancer at varying stages were asked to
breathe into small containers that stored their exhaled breath.
Later, two groups of volunteers sniffed some of each patient’s
exhaled air. The first group of volunteers was human, while the
next group consisted of three Labrador retrievers and two
Portuguese water dogs, all trained to sit or lie down when they
smelled the exhaled breath of a person with cancer. Their results
were compared with results on exhaled breath samples from 83
healthy people.
While dogs are not yet being used to diagnose cancer, the
results of the study were more than promising. The human sniffers
failed to pick up on any of the cancer patients. But for the dogs,
Dr. McCulloch said that "the accuracy in lung cancer was 99% and in
breast cancer it was 88%" -- adding that the accuracy rate was
higher than it is with standard diagnostic methods. He said that
more research is necessary before the canine crew can be put to
work. In particular, there needs to be a comparative study where
the breath sniffing is included during routine cancer screening,
with the outcome evaluated against accepted diagnostic protocols --
and examined after a period of time. A study like this would extend
over, say, five years, when cancer might be either confirmed or
excluded, as this would help to see whether dogs are able to detect
the disease even before symptoms develop.
By the way, the dogs used in the research at Pine Street
aren’t some lab-bred super-pooches -- they are family pets. It
takes two to three weeks to train them, and they work three to five
days a week. After work, they go home. "We've learned that a happy
dog is a more accurate sniffer," Dr. McCulloch said.
Bruce Kimball, PhD, is a chemist with the National Wildlife
Research Center and works with the Monell Chemical Senses Center in
Philadelphia. Monell, a nonprofit research institute, is one of
several organizations looking into new ways of using animals to
detect disease.
At present, Dr. Kimball is working at training mice to
identify the feces of ducks infected with avian influenza, a
disease that can cause illness and death in humans as well as
birds. And, he told me, mice have been taught to successfully
distinguish between animals that have been vaccinated for rabies
and those that haven’t.
Though some people may find all of this surprising, the truth
is that animals’ detection abilities are familiar in other spheres
of life -- police bloodhounds... drug- and explosive-sniffing dogs
at airports and border crossings... rescue dogs searching for signs
of life in the rubble after natural disasters... "service" dogs who
are able to detect imminent seizures. Dr. Kimball said that on
several occasions, dogs have located land mines that were
overlooked by mechanical sensors -- on the other hand, he’s never
heard of a machine that found a mine that a dog had missed. And not
long ago, The New England Journal of
Medicine reported that a cat in a nursing home identified
residents who were near death by making frequent visits to those
patients’ rooms. The operative theory is that the cat could smell
the chemical changes associated with a person’s end-of-life
transition, a process called cellular necrosis, where the body’s
cells begin to degrade.
FROM LABRADORS TO LABORATORIES
Researchers are working at a fast pace and headed in several
directions.
For instance, dogs are being trained to detect a wider range
of diseases. Pine Street Foundation is preparing to study patients
with ovarian cancer -- their breath will undergo both dog-sniffing
tests and chemical analysis. Prostate cancer, skin cancer and
tuberculosis are on the target list of researchers as well. "Any
disease that changes the odor signature of the body will lend
itself to this method," Dr. McCulloch said.
Meanwhile, several organizations are working to develop
technology or laboratory analysis techniques that mimic the sensory
systems of animals in detecting diseases. The University of Maine,
for example, is teaming up with the Pine Street Foundation to
devise a lab tool that analyzes the breath of people suspected to
have cancer to determine whether more testing should be done or
whether they should remain under close observation. And researchers
at Monell have been at work on a mechanical nose that provides this
information.
While science rarely succeeds in duplicating nature, it is not
yet known which -- a device or the real live animal -- will be
better at detecting disease. So in the meantime, think of it as a
nose-to-nose competition!