Trained dog can detect scent of colorectal cancer
MedWire News: Scientists have demonstrated that specially trained dogs can accurately detect the scent of colorectal cancer (CRC) in patient breath and stool samples.
As previously reported by MedWire News, trained dogs have successfully identified prostate and ovarian cancers from patient samples, suggesting that a specific cancer scent may exist.
In this study, Hideto Sonoda (Kyushu University, Fukuoka, Japan) and colleagues obtained 33 breath test samples and 37 watery stool tests from CRC patients and 132 breath and 148 stool samples from healthy volunteers, respectively.
A Labrador retriever dog that had been trained to detect the scent of cancer was allowed to smell 33 and 37 groups of breath and stool samples, respectively, after smelling a separate CRC positive breath or stool sample. The samples were placed in "stations" with one CRC sample and four control samples in each group. The dog smelled all five stations and then sat down in front of the sample it detected as being cancerous.
In total, four discrepancies between the results from colonoscopy and canine scent detection occurred (1 stool and 3 breath tests). This gave a sensitivity and specificity for canine detection of CRC in the breath and stool samples of 0.91 and 0.99 versus 0.97 and 0.99, respectively.
Sonoda and team found that the accuracy of canine CRC detection was high even for patients with early stage cancer and was not confounded by current smoking, or the presence of inflammatory or benign colorectal disease.
"It may be difficult to introduce canine scent judgment into clinical practice owing to the expense and time required for the dog trainer and for dog education," write Sonoda and co-workers in the journal Gut.
"Scent ability and concentration vary between different dogs and also within the same dog on different days. Moreover, each dog can only conduct tests for a maximum of 10 years," they explain.
"It is therefore necessary to identify the cancer-specific volatile organic compounds detected by dogs and to develop an early cancer detection sensor that can be substituted for canine scent judgment," the researchers conclude.
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By Helen Albert