dog 'sniffs out thyroid cancer'

A dog has been used to sniff out thyroid cancer
in people who had not yet been diagnosed, US
researchers say.
Tests on 34 patients showed an 88% success
rate in finding tumours.
The team, presenting their findings at the annual
meeting of the Endocrine Society, said the
animal had an "unbelievable" sense of smell.
Cancer Research UK said using dogs would be
impractical, but discovering the chemicals the
dogs can smell could lead to new tests.
The thyroid is a gland in the neck that produces
hormones to regulate metabolism.
Thyroid tumours are relatively rare and are
normally diagnosed by testing hormone levels in
the blood and by using a needle to extract cells
for testing.
Smelly job
Cancers are defective, out-of-control cells. They
have their own unique chemistry and release
"volatile organic compounds" into the body.
The canine approach relies on dogs having 10
times the number of smell receptors as people
and being able to pick out the unique smells
being released by cancers.
The man's best friend approach has already
produced promising results in patients with
bowel and lung cancers.
A team at the University of Arkansas for Medical
Sciences (UAMS) had previously showed that a
dog could be trained to smell the difference
between urine samples of patients with and
without thyroid cancer.
Frankie gave the correct diagnosis in 30 out
of 34 cases
The next step was to see if it could be used as a
diagnostic test.
Frankie the German Shepherd was trained to lie
down when he could smell thyroid cancer in a
sample and turn away if the urine was clean.
Thirty-four patients, who were going to hospital
for conventional testing, took part in the trial.
Frankie gave the correct diagnosis in 30 out of
34 cases. There were two false positives and
two patients who would have been incorrectly
given the all-clear.
Dr Donald Bodenner, the chief of endocrine
oncology at UAMS, said: "The capability of dogs
to smell minute amounts is unbelievable.
"The medical community over the next few years
is going to have a great appreciation [for them].
E-nose
Some researchers are trying to strip out the
canine-element and test for the unique pong of
cancer with an "electronic nose".
This approach is also being trailed outside of
cancer and has been used to find dangerous
infections such as Clostridium difficile .
Dr Bodenner added: "We would like to know
what Frankie is smelling, nobody knows."
Commenting on the findings Dr Jason Wexler, an
endocrinologist in Washington, DC, argued: "This
is a fascinating, interesting study and it has high
potential in areas of the world that may not have
access to biopsy techniques.
"There are many patients who are reluctant to
undergo fine needle aspiration so I think that if
you could design a technique where you have no
invasive procedure that can have tremendous
widespread appeal."
But Dr Emma Smith, from Cancer Research UK,
cautioned: "Although there's some evidence that
some trained dogs can sniff out the smelly
molecules given off by cancers, there have been
mixed results on how accurate they are and it's
not really practical to think about using dogs on
a wide scale to detect the disease.
"But carrying out lab tests to understand what
the dogs are smelling might help to inform the
development of 'electronic noses' to detect the
same molecules, which could lead to better
diagnostic tests in the future."
Dr Bodenner says it is an approach that he is
actively pursuing.
Meanwhile, the lab is also trying to find a new
home for canine-veterans from Iraq and
Afghanistan.
Instead of sniffing out bombs, they will be
trained to hunt for cancer.
Symptoms of thyroid cancer
A painless lump or swelling at the front of
the neck below the Adam's apple
Unexplained hoarseness that doesn't get
better after a few weeks
Sore throat or difficulty swallowing that
doesn't get better
Pain in the neck