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 can be used for 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 .
The researchers from Germany believe Schillerhoehe Hospital in dogs can be better at picking up cancer cases with more skill .
But the ultimate goal is to identify cancer - specific chemical compounds the dogs can smell and develop a device that can be used to help victims diagnose lung cancer at an earlier stage .
Lung cancer is the biggest cancer killer Britain has more than 39,000 cases diagnosed annually , of which only 25 percent will survive a year because the disease is usually found in 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 .
Attempts to locate the volatile organic compounds ( VOCs ) in breath linked to the presence of cancer , but no reliable methods have been made so far to the lungs - definitely .
The researchers combined this method with recent findings about the ability of some dogs to alert their owners to undiagnosed cancer , perhaps by smell .
This latest study used family dogs including German and Australian shepherds and a Labrador retriever , given special training over a period of 11 - weeks to identify a VOC in the breath of patients .
The researchers worked with 220 volunteers , including patients with lung cancer in early and advanced stages , patients with chronic obstructive pulmonary disease and healthy volunteers .
The dog took part in a number of tests to see if they can reliably identify 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 taking part and had to lie down if they see 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 .
The dogs can also see lung cancer independently from COPD , prescription drugs and tobacco smoke , says a report in the European Respiratory Journal .
Tagapagpananaliksik say the findings confirm the presence of a stable marker for lung cancer - but the drawback is they do not know what it is .
Study leader Thorsten Walles from Schillerhoehe Hospital , said " In the breath of patients with lung cancer , there are likely to be different chemicals to normal breath samples and the dogs ' keen sense of smell can see this difference at an early stage of the disease .
" Our results confirm the presence of a stable marker for lung cancer . This is a big step forward in the diagnosis of lung cancer , but we still need to accurately identify the compounds observed in the exhaled breath of patients .
" It is unfortunate that dogs can not communicate the biochemistry of the scent of cancer ! "
Thoracic surgeon and fellow tagapagpananaliksik Enole Boedeker said the dog was very excited by the ' game ' and is rewarded by Treat when they got it right .
He said ' The trainer would shout ' Cancer - go ' and off they went , sometimes identifying a VOC immediate and other times they hesitated and then went back .
' Had it around 11 weeks of training but seems to get better the more they made , I think I can go much higher rate of success .
' However , that they are trained in a certain way using samples so even if they go to a room with a man who had lung cancer can be difficult for them to register , which is why we need to investigate a screening tool 'he added .
In the past , research reports and anecdotal suggested dogs - usually Labrador retrievers and Portuguese water dogs - can sniff out bladder , skin , lung , breast and ovarian cancer .
Patients with breast and lung cancer are known to exhale patterns of biochemical markers in their breath , which can be traced to the tumor to leak small amounts of chemicals are not found in healthy tssue .
Trained dogs also took up skin cancer melanomas by sniffing skin lesions , while even domestic pets raised the alarm with agitated behavior which led their owners to seek medical advice .
The researchers acknowledged that it can be difficult to use dogs in clinical practice because of the cost and time it takes to train them .
But they hope to cancer - specific compounds detected by dogs be associated with a new sensor that can be used to test the stool and breath samples as part of the screening .
Professor Stephen Spiro , deputy chairman of the British Lung Foundation and lung cancer specialist , said " A dog is said to be best friends with someone and this breakthrough could show that our canine counterparts can offer more inclusion .
" The patients in the study were diagnosed with lung cancer , the most advanced being . The real question is how this technique can be used to identify those with a high risk of getting lung cancer , such as male ex - smoker and those with chronic obstructive pulmonary disease ( COPD ) . '