Dogs can detect cancer
 A
trained dog can detect the odour of bowel cancer in breath and stool
samples to a high level of accuracy, even in the early stages, according
to researchers in Japan who hope this will lead to new ways of screening
for the disease, not necessarily using dogs, but based on the principle
that cancer tumors secrete specific volatile compounds that can be
detected with equipment as sensitive as a dog's nose.
A paper published online first on January 31 in the journal Gut
outlines how Hideto Sonoda, assistant professor at Kyushu University at
Fukuoka, and colleagues, carried out their study, aided by Marine, a
9-year-old female Labrador retriever, specially trained in scent
detection of cancer.
Previous studies have already reported that trained dogs can sniff
out melanoma, bladder, lung, breast and ovarian cancer.
For example, using just breath samples in the case of lung and breast
cancer, and tissue samples in the case of ovarian cancer, trained dogs
can tell the difference between samples from cancer patients and healthy
volunteers to a high level of accuracy.For this study, which took place
between November 2008 and June 2009, the researchers obtained exhaled
breath and watery stool samples from patients with colorectal cancer (CRC)
and healthy controls before they underwent a diagnostic test with a
colonoscopy.
There were 33 groups of breath samples and 37 groups of stool
samples, each group comprising one sample from a patient with CRC, and
four control samples from volunteers who were free of cancer.
The samples were randomly separated and put into five boxes. Marine,
who was trained at the St Sugar Cancer Sniffing Dog Training Center at
Minamibousou, Chiba, in Japan, and her handler were then given the task
of picking out a box. Marine first smelled a standard breath sample from
a different patient who definitely had CRC (not included in the test
samples), and then sniffed each of the test boxes, and sat down in front
of the box that smelled like the standard sample.
The results showed that:
* For both the breath and the stool samples, Marine showed high
accuracy in picking out the CRC sample, compared to diagnosis by
colonoscopy (the dog was correct more than nine times out of ten).
* In the case of the breath samples, the sensitivity of "canine scent
detection" was 0.91 and the specificity was 0.99.
* In the case of the stool samples, the accuracy was even greater:
sensitivity was 0.97 and specificity was 0.99.
* The accuracy was high even for early cancer, wrote the researchers,
and these results were unchanged when they took into account current
smoking, benign bowel disease or inflammatory disease, or the presence
of human haemoglobin or transferrin.
The resarchers concluded that their findings show that there is a
specific scent for cancer, and that cancer-specific chemicals could be
circulating in the bodies of people with cancer.
"These odour materials may become effective tools in CRC screening,"
they wrote. Studies that identify cancer-specific volatile organic
compounds will play an important role in opening up opportunities to
develop new ways of detecting bowel cancer early, they added
Courtesy: Medical News Today
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