The study reveals that Frankie – a male German Shepherd-mix – correctly identified the thyroid cancer status of 30 out of 34 human urine samples.
The future of cancer screening may not be in expensive, invasive tests, but simply in having dogs sniff a urine sample. In a new study conducted by researchers from the University of Arkansas for Medical Sciences (UAMS) and presented at the 97th Annual Meeting of The Endocrine Society in San Diego, a rescue dog name Frankie had a 90 percent success rate at distinguishing between urine from people with thyroid cancer and urine from people without the disease.
Although many dogs have previously been trained to detect various human cancers, Frankie is the first dog trained to differentiate between people who have benign thyroid disease and those who have cancer simply by sniffing their urine.
As accurate as current top test
Currently, the preferred method to diagnose thyroid cancer is a fine-needle aspiration biopsy, which includes inserting a thin needle through the neck and into the thyroid gland to remove thyroid tissue for analysis.
Yet many diagnostic techniques have less than perfect accuracy, leading to many unnecessary thyroid surgeries, according to senior researcher Donald Bodenner.
In an effort to provide an alternative to such invasive tests, the researchers trained Frankie, a German Shepherd mix, to recognize the smell of cancerous human thyroid tissue. He had been trained to lie down when he smelled cancer, and to turn away when he did not.
They then collected urine samples from 34 patients at the UAMS thyroid clinic. All the participants then underwent biopsies and diagnostic surgery, which confirmed that 15 of them had thyroid cancer and the other 19 had benign thyroid disease. These results were kept secret from the researchers and the dog handler used in the next part of the study.
A gloved dog handler had Frankie sniff the urine samples (with occasional breaks to sniff a known cancerous sample in order to be rewarded for correct identification and keep him motivated to continue). Frankie correctly identified 30 of the 34 samples.
He had only two false negatives, and two false positives. This accuracy was comparable to that of fine-needle aspiration biopsy.
“Scent-trained canines could be used by physicians to detect the presence of thyroid cancer at an early stage and to avoid surgery when unwarranted,” Bodenner said.
The researchers are now planning a followup study in conjunction with Auburn University College of Veterinary Medicine, which has assigned two bomb-sniffing dogs to be trained in cancer detection.
Dogs, bees and fruit flies
The use of dogs or other animals to detect cancer is a burgeoning field of research. The rationale is simple: While humans have only 5 million scent receptors in their noses, dogs have about 200 million, giving them a sense of smell roughly a thousand times more sensitive.
In a 2011 study, researchers successfully trained dogs to detect lung cancer by sniffing patients’ breath. Notably, the dogs could detect cancer even when those patients had been smoking or had chronic obstructive pulmonary disease, unlike current cancer screening tests. In 2014, a study showed that dogs had 98 percent accuracy at detecting prostate cancer from urine samples. Dogs are also being trained to detect ovarian cancer.
Other animals can also be taught cancer detection. In a study published in the journal Scientific Report in February 2014, researchers from the University of Konstanz in Germany and the University La Sapienza in Italy reported that they had trained fruit flies to not only smell the difference between healthy and cancerous human cells, but even to smell the difference between various cancer strains. And according to a 2013 study, bees have been successfully trained to detect not just cancer, but even tuberculosis and diabetes just by breathing air exhaled by the human patients.