While Japan is known to have higher than average rates of stomach cancer, the residents of the town of Kaneyama in Yamagata Prefecture appear to be particularly susceptible to the gastric ailment. After a recent report revealed that the municipality had one of the highest stomach cancer fatality rates out of the nation’s 344 “secondary medical districts,” the town officials decided to get its 6,000 residents tested.
However, the frozen urine samples submitted to the Nippon Medical School Chiba Hokusoh Hospital in Chiba Prefecture, east of Tokyo, are not undergoing conventional diagnostic tests. Instead, Professor Masao Miyashita and his team are using them in a trial to determine if specially trained cancer-sniffing dogs can accurately detect the disease. Though the study is still in its early stages, Miyashita is thrilled with the results saying, “In our research so far, cancer detection dogs have been able to find [signs of] cancer with an accuracy of nearly 100 percent."
The animal’s ability to sniff out the disease can be attributed to the 300 trillion sensors in its nose. In contrast, humans only have 6 million sensors. Pooches also have a second smell receptor that we do not possess. Located at the bottom of their nasal passage, the vomeronasal, or Jacobson's, organ, is powerful enough to smell generally undetectable odors. Claire Guest, the founder and CEO of Medical Detection Dogs, says, “They [dogs] can detect parts per trillion — that’s the equivalent of one drop of blood in two Olympic-sized swimming pools.”
Researchers have known about the animals’ superior sensory skills for decades. However, their ability to detect cancer in humans came to light in 1989, after a dog sniffed out early stage malignant melanoma from a mole on a patient’s leg at King’s College in London. Since then, scientists from France to California to Italy have conducted studies to test the canine’s prowess at identifying cancer chemicals.
One of the biggest studies was undertaken by Medical Detection Dogs in 2016. For the trial, cancer-sniffing dogs were exposed to several batches of evenly placed urine samples. Each contained one belonging to a cancer patient. To ensure the dogs were sniffing out cancer and not something else, like old age, each group included a urine sample from a similarly-aged candidate who was experiencing cancer-like symptoms but did not have the disease. Sure enough, the dogs were able to identify the cancer sufferer each time. Since then, the nonprofit organization has trained pooches to detect all kinds of cancers, from prostate to breast. They are now conducting trials to see if the animals can help diagnose Parkinson’s disease early.
While most dogs can be trained for the task, researchers say the best candidates are pooches that are precise, methodical, quiet, and perhaps even a little shy. The training process is similar to how canines are taught to learn any trick — by rewarding them with treats! However, it takes much longer because the dogs have to learn to isolate the “cancer scent” from the thousands of organic compounds in the human body. Researchers begin by exposing the canines to urine samples from people with cancer, people with other ailments, and patients with no health issues. Once the dogs are able to identify accurately cancer, they are further trained to detect particular kinds of cancer.
Successful as they may be, experts think dogs are unlikely to replace conventional diagnostic tests. For one, it takes about seven years and costs as much as $45,000 USD to train a single dog. Klaus Hackner, a researcher and physician who studies dogs detecting cancer in breath samples at Krems University in Austria, is also not convinced pooches can be relied upon alone. Patients, therefore, have to undergo further tests to confirm if they have the disease.
Guest acknowledges that dogs will always be used in conjunction with traditional tests. However, the researcher is still a big proponent of training the animals given that they can sniff out the disease long before the symptoms appear. And she should know — after all it was her dog Tangle’s superior sniffing skills that led to the early discovery of a deep-rooted cancer tumor insider her breast tissue in 2009.
Resources: CNN.com,smitsonianmag.com,medicaldetectiondogs.org.uk
