For sure these trained dogs are more expensive!
Dogs are kwnon as our best friends.
But it works unfortunately only for few.
They already use rats for their nose, I'm not sure what disease it was, TBC or cancer.
so how do you smell cancer? Don't the cells smell the same as normal ones?
Ah, here's the answer:
Tomorrow's *New York Times* includes an article: "Dogs Excel on Smell Test
to Find Cancer" by Donald McNeil.
Here's the article:
In the small world of people who train dogs to sniff cancer, a little-known
Northern California clinic has made a big claim: that it has trained five
dogs - three Labradors and two Portuguese water dogs - to detect lung cancer
in the breath of cancer sufferers with 99 percent accuracy.
The study was based on well-established concepts. It has been known since
the 80's that tumors exude tiny amounts of alkanes and benzene derivatives
not found in healthy tissue.
Other researchers have shown that dogs, whose noses can pick up odors in the
low parts-per-billion range, can be trained to detect skin cancers or react
differently to dried urine from healthy people and those with bladder
cancer, but never with such remarkable consistency.
The near-perfection in the clinic's study, as Dr. Donald Berry, the chairman
of biostatistics at M. D. Anderson Cancer Center in Houston, put it, "is off
the charts: there are no laboratory tests as good as this, not Pap tests,
not diabetes tests, nothing."
As a result, he and other cancer experts say they are skeptical, but
intrigued. Michael McCulloch, research director for the Pine Street
Foundation in Marin County, Calif., and the lead researcher on the study,
acknowledged that the results seemed too good to be true. (For breast
cancer, with a smaller number of samples, the dogs were right about 88
percent of the time with almost no false positives, which compares favorably
"Yes, we were astounded, as well," Mr. McCulloch said. "And that's why it
needs to be replicated with other dogs, plus chemical analysis of what's in
He is applying for National Science Foundation grants to try just that, he
said. The fact that the study was carried out by a clinic supported by the
Pine Street Foundation that combines traditional chemotherapy with
acupuncture and herbal medicine raised suspicions, as did the fact that it
is to be published by a little-known journal, Integrative Cancer Therapies.
(The journal published it online last year.)
But experts who read the study could not find any obvious fatal flaw in its
methodology, and the idea that dogs can detect cancer is "not crazy at all,"
said Dr. Ted Gansler, director of medical content in health information for
the American Cancer Society. "It's biologically plausible," he said, "but
there has to be a lot more study and confirmation of effectiveness."
Dr. Berry, too, was interested but suspicious. "If true, it's huge," he
said. "Which is one reason to be skeptical."
Dr. Berry noted, half-jokingly, that Gregor Mendel, the 19th-century
discoverer of the laws of genetics, also reported data on his crossbreeding
of green and yellow peas that was too good to be true: he repeatedly came up
with the perfect 3-1 ratios he predicted. "But we've forgiven Mendel and his
gardener," Dr. Berry added, "because his theory turned out to be right."
In Mr. McCulloch's study, the five dogs, borrowed from owners and Guide Dogs
for the Blind, were trained as if detecting bombs. They repeatedly heard a
clicker and got a treat when they found a desired odor in many identical
The clinic collected breath samples in plastic tubes filled with
polypropylene wool from 55 people just after biopsies found lung cancer and
from 31 patients with breast cancer, as well as from 83 healthy volunteers.
The tubes were numbered, and then placed in plastic boxes and presented to
the dogs, five at a time. If the dog smelled cancer, it was supposed to sit.
For breath from lung cancer patients, Mr. McCulloch reported, the dogs
correctly sat 564 times and incorrectly 10 times. (By adjusting for other
factors, the researchers determined the accuracy rate at 99 percent.)
For the breath from healthy patients, they sat 4 times and did not sit 708
Experts who read the study raised various objections: The smells of
chemotherapy or smoking would be clues, they said. Or the healthy breath
samples could have been collected in a different room on different days. Or
the dogs could pick up subtle cues - like the tiny, unintentional movements
of observers picked up by Clever Hans, the 19th-century "counting horse," as
he neared a correct answer. But Mr. McCulloch said cancer patients who had
begun chemotherapy were excluded, smokers were included in both groups and
the breath samples were collected in the same rooms on the same days. The
tubes were numbered elsewhere, he said, and the only assistant who knew
which samples were cancerous was out of the room while the dogs were
"The fact that dogs did this is kind of beside the point," he said. "What
this proved is that there are detectable differences in the breath of cancer
patients. Now technology has to rise to that challenge."
The next step, he said, will be to analyze breath samples with a gas
chromatograph to figure out exactly which mixes of chemicals the dogs are
Even if the dogs are accurate in repeat experiments, Dr. Gansler of the
American Cancer Society said, it will be useful only as a preliminary scan.
"It's not like someone would start chemotherapy based on a dog test," he
said. "They'd still get a biopsy."
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