Dogs can sniff out cancer

18th August 2011 -- Sniffer dogs could be used for the early detection of lung cancer, according to new research in Germany.

The study, which is published in the European Respiratory Journal, is the first of its kind to find that dogs can reliably detect the disease on people’s breath.

Lung cancer most common cancer killer

Lung cancer is the second most common cancer (after breast cancer) in England and Wales, with an estimated 31,000 new cases diagnosed every year. It is the most common cause of cancer-related death in both men and women. During 2007, there were 29,660 deaths in England and Wales due to lung cancer.

Smoking is the single biggest risk factor for lung cancer, accounting for an estimated 85-90% of cases.

Hard to detect

The disease is not strongly associated with any symptoms and early detection is often by chance. Current methods of detection can be unreliable, and scientists have been working on using exhaled breath specimens from patients for future screening tests.

This method relies on identifying volatile organic compounds (VOCs) that are linked to the presence of cancer. It is still difficult to apply in a clinical setting as patients aren't allowed to smoke or eat before the test, sample analysis can take a long time, and there is also a high risk of interference.

This new German study looked at whether or not sniffer dogs could be used to identify a VOC in the breath of patients.

Study results

The researchers worked with 220 volunteers, including lung cancer patients, chronic obstructive pulmonary disease (COPD) patients and healthy volunteers. They used dogs that had been specifically trained. The researchers carried out a number of tests to see if the dogs were able to reliably identify lung cancer compared with healthy volunteers, volunteers with COPD and whether the results were still found with the presence of tobacco.

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 detect lung cancer independently from COPD and tobacco smoke.

Hopes for the future

Study author Thorsten Walles from Schillerhoehe Hospital says, "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!"

Commenting on new research, Professor Stephen Spiro, Deputy Chair of the British Lung Foundation and lung cancer specialist, says, "A dog is said to be man’s best friends 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 high risk of getting lung cancer, such as male ex-smokers and those with chronic obstructive pulmonary disease (COPD.)"