Dogs can be trained to identify the scent of lung cancer long before symptoms develop, say researchers.
The uncanny canine ability to detect smells that escape the human nose could be used for the early detection of lung cancer, according to new study.
It is the first to show that sniffer dogs can be relied upon to find the unique smell of the disease in seven out of 10 sufferers.
Researchers from Schillerhoehe Hospital in Germany believe dogs could become even better at picking up cancer cases with more practice.
But the ultimate goal is to identify the cancer-specific chemical compounds the dogs can smell and develop a device that could be used to help diagnose lung cancer victims at an earlier stage.
Lung cancer is Britain's biggest cancer killer with over 39,000 cases diagnosed annually, of which only 25 per cent will survive a year because the disease is mostly found at an advanced stage when it is very difficult to treat.
Early detection is often by chance, although scientists have been working on using exhaled breath specimens from patients for future screening tests.
These attempt to locate volatile organic compounds (VOCs) in the breath that are linked to the presence of cancer, but no reliable methods have been devised so far that are lung-specific.
The researchers combined this approach with recent findings about the ability of some dogs to alert their owners to undiagnosed cancer, probably through smell.
This latest study used family dogs including German and Australian shepherds and a Labrador retriever, which were given special training over an 11-week period to identify a VOC in the breath of patients.
The researchers worked with 220 volunteers, including patients with lung cancer at early and advanced stages, patients with chronic obstructive pulmonary disease and healthy volunteers.
The dogs took part in a number of tests to see if they could reliably distinguish compounds in the breath of lung cancer patients – even if they smoked.
The dogs were asked to sniff glass tubes containing cotton impregnated with samples of breath from those taking part and had to lie down if they detected a VOC from a lung cancer patient.
The dogs successfully identified 71 samples with lung cancer out of a possible 100. They also correctly detected 372 samples that did not have lung cancer out of a possible 400.