Cancerous cells produce a very specific odor. In fact, in late stages of the disease, even human noses can detect it. With a sense of smell researchers estimate is between 10,000 and 100,000 times superior to ours, dogs can detect this smell far earlier in the disease’s progress—even while the cancer is still “in situ,” or has not spread from the site where it was first formed. And remarkably, they don’t need to smell the growth directly. Dogs can detect this scent on waste matter like breath.
We all know dogs possess incredible powers of smell. Some have even been trained to sniff out diseases like diabetes and cancer. But exactly how is this superpower being put into practice by research centers and healthcare providers around the country? Cancer-detecting canines and their handlers across the country offer the lowdown on the latest life-saving adventures of man’s best friend.
Another dog from In Situ’s program, Yellow Labrador Retriever Enloe is supported by the Enloe Medical Center and Enloe Regional Cancer Center in Chico, where In Situ is based. Enloe is something of a local celebrity, with people around Chico following his training. He’s extremely driven for food and toys, which makes him a great cancer-detection dog, as he’s always keen to get his reward. Enloe has a loving family in the community to go home to every night after a fun day’s work training to detect cancer.
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Each In Situ dog trains for up to eight months, smelling samples of breath, plasma, urine, and saliva collected by doctors and sent to the foundation. After smelling more than 300 unique samples, dogs are able to distinguish between a healthy sample and a cancerous one. They also learn to “generalize” the smell, meaning they can transfer what they know about the smell from samples already tested to new, similar samples.
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Wall Street Journal reporter Daniela Hernandez spotlights the work of Media Lab Research Scientist Andreas Mershin in developing sensors that can detect and analyze odors. Mershin “is focusing on medical applications of olfaction technology. Inspired by dogs that have demonstrated an ability to sniff out malignancies in humans, he’s working on an artificial-intelligence odor-detection system to detect prostate cancer.”
Reflecting on how he became involved in this research, Mershin recalled a study of bladder cancer detection, in which a dog kept misidentifying one member of the control group as being positive for the disease, even though he had been specifically selected based on hospital tests as being disease free. The patient, who knew about the dog’s test, opted to have further tests, and a few months later was found to have the disease at a very early stage. “Even though it’s just one case, I have to admit that did sway me,” Mershin says.
While the physical apparatus for detecting and analyzing the molecules in air has been under development for several years, with much of the focus on reducing its size, until now the analysis was lacking. “We knew that the sensors are already better than what the dogs can do in terms of the limit of detection, but what we haven’t shown before is that we can train an artificial intelligence to mimic the dogs,” he says. “And now we’ve shown that we can do this. We’ve shown that what the dog does can be replicated to a certain extent.”
This achievement, the researchers say, provides a solid framework for further research to develop the technology to a level suitable for clinical use. Mershin hopes to be able to test a far larger set of samples, perhaps 5,000, to pinpoint in greater detail the significant indicators of disease. But such testing doesn’t come cheap: It costs about $1,000 per sample for clinically tested and certified samples of disease-carrying and disease-free urine to be collected, documented, shipped, and analyzed he says.
How Do Dogs Act When They Smell Cancer?
“The ability of dogs to detect melanoma, a potentially fatal skin cancer, has been formally studied and confirmed,” says Ashley Stenzel, PhD, a Roswell Park postdoctoral fellow. Dr. Stenzel notes that in case studies, dogs persistently sniffed, licked and nipped at melanoma lesions on their owners’ skin, even through clothing, prompting the owners to identify the cancerous sites and seek care from clinicians. “Given that melanoma is a cancer presenting with lesions on the skin, it would be logical for dogs to be able to detect a lesion,” Dr. Stenzel says. “However, the use of canine olfactory detection has also been studied in other examples of cancer.”
Lauren credits her dog, Victoria, for calling attention to a bump on her nose, which turned out to be basal cell carcinoma.
In one widely noted anecdotal case, Lauren Gauthier, founder of Magics Mission hound rescue organization, reported that Victoria, her adopted Treeing Walker Hound, “persistently sniffed and stared at what seemed like a pimple on my right nostril. It was so odd and she was so persistent that I finally decided to have it checked out.” The “bump” ended up being basal cell carcinoma, a common type of skin cancer. “As soon as I had Mohs surgery to remove the cancer, Victoria’s strange behavior stopped.”
Claire Guest, MSc, DHP, BCAh, CEO of Medical Detection Dogs, recalls that Daisy, her Fox Red Labrador, who is trained to sniff out cancer in the lab, kept staring and pawing at her chest. While trying to decipher Daisy’s behavior, Dr. Guest discovered a lump that turned out to be a malignant tumor deep in her breast.
In Being a Dog, Horowitz describes a Dachshund puppy that repeatedly sniffed her owner’s armpit. Eventually the woman found a lump in her armpit, leading to a breast cancer diagnosis.