With powers of smell far superior to those of humans, dogs have been trained to smell bombs, drugs, missing people, corpses — and, more recently, cancer. Scientists in Japan last week reported that with a trained Labrador retriever could outperform a standard blood test in detecting colorectal cancer.

The research team, led by Hideto Sonoda of Kyushu University, enlisted a dog named Marine to sniff out colorectal cancer in the breath and stool samples. Writing in the journal Gut, Sonoda and his colleagues report that the pooch detected cancer in 37 out of 38 fecal samples, compared to just 25 positively identified by a standard laboratory assay known as the fecal occult blood test.

The results comes at the heels of another study, published in this month’s issue of European Urology, showing that a Belgian Malinois could correctly identify prostate cancer in urine samples more than nine times out of ten. In 2006, a team led by Michael McCulloch, a cancer oncologist at the Pine Street Foundation near San Francisco, also posted comparable success with using dogs to detect breast and lung cancer in human breath.

The Japanese team now plans to deploy Marine to track down the key scents in their biological specimens in hopes of designing a new machine-based test that can more accurately and non-invasively detect colorectal cancer.

“This is the kind of research that needs to be done to evaluate smell as a diagnostic test, whether you are talking dog or machine,” McCulloch told Nature Medicine.

But McCulloch sees no reason to take the dogs off the scent of cancer, noting that two tests are better than one for increasing accuracy and sensitivity. Plus, he points out, the canine cancer detectives can sniff out a range of diseases, from hypoglycemia to epilepsy. “A technology will provide only what you ask it,” he says. “Dogs can provide you more than the information you can ask for.”

To find out more about how researchers are looking to Mother Nature to ferret out disease, read our news story in this month’s issue of the journal.

Image: Just Add Light, Flickr