Here's another reason to bring home a canine best friend. With a little bit of training, ordinary pet dogs can sniff out cancer in humans by taking a whiff of their breath, a new study by cancer research group Pine Street Foundation, has found.
“Our study provides compelling evidence that cancers hidden beneath the skin can be detected simply by (dogs) examining the odors of a person's breath,” said Michael McCulloch, lead author of the study. “We've seen anecdotal evidence before suggesting that dogs can smell the presence of certain types of cancer, but until now, nobody had conducted a thorough study such as this,” he added. The finding might be due to the fact that cancerous cells release molecules different from those by healthy cells, leading to distinct odors that are caught by the strong smelling abilities of a dog.
Under the experiment, McCulloch and his team trained five dogs, three Labradors and two Portuguese water dogs, aged between 7 and 18 months, to give different responses to the breath samples of cancer patients and healthy controls. “The dogs learned to sit or lie down in front of cancer patient samples and to ignore control samples through the method of food reward,” said McCulloch explaining the experiment.
These five dogs were then made to sniff out breath samples of 55 lung cancer patients, 31 breast cancer victims and 83 healthy people. In a whopping 90 per cent of the cases, the dogs gave correct response to the breath samples, distinguishing those of cancer patients from samples of healthy ones easily.
“Cancer cells emit different metabolic waste products than normal cells. The differences between these metabolic products are so great that they can be detected by a dog's keen sense of smell, even in the early stages of disease,” explained Nicholas Broffman, executive director of the California-based Pine Street Foundation. Added McCulloch, “We actually don't know what the dogs are smelling. But we do know that cancers have breakdown products – cocktails of compounds – and these smell different to a dog than normal cells.”
Hailing the study, James Walker of the Sensory Research Institute at Florida State University said that dogs possess a keen sense of smell, one that is 10,000 to 100,000 times stronger than that of humans. “This is not a goofy idea at all. You have to remember that years ago physicians used their sense of smell to diagnose patients,” he added.
McCulloch said that further research is required to see if the dogs can detect ovarian and pancreatic cancers, which are tough to diagnose early. “These results show that there is hope for early detection. I hope people will be interested in pursuing this research. It shows that there is definitely something out there,” he said.
Walker added that using dogs could be tried as an experimental treatment. “There are lots of experimental treatments. This could be an experimental diagnostic tool for a while, and one that is impossible to hurt anyone with or to mess up their diagnosis with,” he said. The findings of the study have been published in
Integrative Cancer Therapies.
Earlier, a study by Amersham Hospital in Buckinghamshire researchers had shown that dogs could tell urine from a bladder cancer patient apart from that from a healthy person. Several incidents have also been reported where pet-owners were diagnosed with skin cancers after their dogs kept sniffing their skin lesions, leading them to seek a doctor's opinion.
