A different kind of Lab test to identify colorectal cancer


The doctor will see you now – and she has four legs and a tail.

That’s right. Japanese researchers have trained an 8-year-old Labrador retriever to diagnose colorectal cancer by smelling a patient’s breath and/or poop. The Lab (who previously worked as a water rescue dog) had an overall accuracy of 95% when using the breath test and 98% for the stool test, according to a study published Monday in the journal Gut.

To train the dog, researchers first let her sniff a breath sample from a patient with colorectal cancer. Then they presented her with a panel of breath samples – one from a cancer patient and four from healthy people. When the Lab recognized the sample from the cancer patient, the reward was some quality time with a tennis ball.

In the Gut study, the dog was presented with 36 panels of breath samples. Overall, she correctly identified 91% of the samples that were from cancer patients, and she correctly ignored 99% of the samples that were from healthy volunteers.


The Lab did a better job evaluating 38 panels of stool samples. In those tests, she correctly flagged 97% of the samples from cancer patients and correctly ignored 99% of the samples that were disease-free.

“This study presents the first step towards the development of an early detection system using odour materials from patients with CRC [colorectal cancer],” the study authors wrote.

The researchers speculate that the dog’s highly developed sense of smell allowed her to pick up a whiff of the chemical compounds that are unique to cancer. It’s still unclear whether each cancer has its own chemical signature, or whether the same compounds are present in a variety of cancers. The researchers note, however, that this particular Lab has been able to detect breast, lung, prostate, uterine, ovarian, bladder, gastric, pancreatic and esophageal cancers from breath samples, along with hepatocellular carcinoma and cholangiocarcinoma.

You can read the full study here.

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