sniffer dogs

Sniffer dogs can detect lung cancer.

Dogs can be trained to accurately identify the scent of lung cancer long before symptoms develop, according to 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.

The dogs could also detect lung cancer independently from COPD, prescription drugs and tobacco smoke, says a report in the European Respiratory Journal.

The researcher say the findings confirm the presence of a stable marker for lung cancer – but the snag 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 detect 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 precisely identify the compounds observed in the exhaled breath of patients.

‘It is unfortunate that dogs cannot communicate the biochemistry of the scent of cancer!’

Thoracic surgeon and fellow researcher Enole Boedeker said the dogs were very excited by the ‘game’ and were rewarded by treats when they got it right.

She said ‘The trainer would shout ‘Cancer – go’ and off they went, sometimes identifying a VOC straight away and at other times they hesitated and then went back.

‘They had around 11 weeks of training but seemed to get better the more they did, I think the success rate could go higher.

‘However, they have been trained in a certain way using samples so even if they did go into a room with someone who had lung cancer it might be difficult for them to register it, which is why we need to investigate a screening tool’ she added.

Previously, research and anecdotal reports suggested dogs – usually Labrador retrievers and Portuguese water dogs – can sniff out bladder, skin, lung, breast and ovarian cancers.

Lung and breast cancer patients are known to exhale patterns of biochemical markers on their breath, which can be traced to tumours which exude tiny amounts of chemicals not found in healthy tssue.

Trained dogs have also picked up skin cancer melanomas by sniffing skin lesions, while even domestic pets have raised the alarm with agitated behaviour that led their owners to seek medical advice.

The researchers acknowledge that it might be difficult to use dogs in clinical practice due to the expense and time it takes to train them.

But they hope that cancer-specific compounds detected by dogs could be incorporated into a new sensor which could be used to test stool and breath samples as part of screening.

Professor Stephen Spiro, deputy chairman of the British Lung Foundation and lung cancer specialist, said ‘A dog is said to be a man’s best friend and this breakthrough could show that our canine counterparts could offer more than companionship.

‘The patients in the study were already diagnosed with lung cancer, the majority being advanced. The real question will be how this technique could be used to identify those at a high risk of getting lung cancer, such as male ex-smokers and those with chronic obstructive pulmonary disease (COPD).’

Photo credit: My Trinity

Via Daily Mail