To reach this conclusion, an experiment was carried out with aspecially trained labrador retriever, who carried out smell tests for several months, includingbreath test and stool samplesof the participants. The samples belonged to 48 people diagnosed with bowel cancer and 258 volunteers who did not have the disease or who had had cancer in the past. About half of the volunteer samples came from people with bowel polyps that, although benign, are considered precursors to bowel cancer.
The dog successfully identified which ones were cancerous and which were not in 33 of 36 breath tests and 37 of 38 stool tests, with the highest detection rates among those drawn from people who had the disease in its early stages. This is equivalent, according to the study, to95% accuracy overall for breath samples and 98% for stool samples, compared to the results obtained from conventional colonoscopies.
The study authors conclude thatthere are chemical constituents corresponding to specific cancers that circulate in the human body and that a dog can smell. This theory is supported by other research that dogs can sniff out bladder, skin, lung, breast and ovarian cancer. Although scientists admit that using dogs to diagnose cancer is probably impractical, they suggest that this finding could developa sensor to be able to detect the disease before it has been able to spreadto other parts of the body.
