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Dogs Sniff Out Early Signs of Colorectal Cancer in Breath or Stool Samples
By Jennifer Warner
WebMD Health News
Reviewed by Laura J. Martin, MD
Jan. 31, 2011 -- Specially trained dogs may be able to sniff out early signs of colorectal cancer in breath or stool samples, according to a new study.
Although canine cancer detection units aren't likely any time soon, researchers say the findings suggest there are particular scents and volatile compounds associated with colorectal cancer that may help them come up with better ways to diagnose the often hard-to-detect and deadly disease.
"This study shows that a specific cancer scent does indeed exist and that cancer-specific chemical compounds may be circulating throughout the body," researcher Hideto Sonoda, of Fukuoka Dental College Hospital in Fukuoka, Japan, and colleagues write in Gut. "These odor materials may become effective tools in CRC [colorectal cancer] screening."
The study showed a Labrador retriever trained in scent detection was able to distinguish between cancerous and noncancerous stool and breath samples in 98% and 95% of cases, respectively.
In the study, the Labrador retriever completed 74 sniff tests, consisting of sniffing five breath or stool samples at a time in which one was cancerous, over a period of several months.
The samples came from 48 people with confirmed colorectal cancer and 258 volunteers with no cancer. Half of the comparison samples came from people with bowel polyps, which are benign growths that are thought to be a precursor of colorectal cancer.
The dog correctly identified the cancerous samples in 33 out of 36 of the breath tests and 37 of 38 stool tests.
Researchers say samples from smokers and other types of gut problems like inflammatory bowel disease or ulcers that might be expected to mask or interfere with scent detection did not pose a problem for the dog.
If further studies confirm these results, researchers say less invasive colorectal cancer screening alternatives to colonoscopy may be developed using cancer-specific volatile organic compounds.
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