Breath test

New Delhi, Aug. 18: Benny can smell lung cancer in human breath samples.

The two-year-old Australian shepherd dog is among four sniffer dogs in Germany trained to detect lung cancer in breath samples of patients, their predictions of the disease matching standard medical diagnosis seven out of 10 times.

A team of doctors and dog trainers has trained sniffer dogs to distinguish between breath samples of healthy persons and lung cancer patients. Their experiments are described in today’s issue of the European Respiratory Journal.

The doctors are not proposing the use of dogs for clinical diagnosis but believe that their experiments could lead to new strategies for the early diagnosis of this common cancer. The tests with the sniffer dogs confirm the presence of a detectable marker — a volatile organic compound — in the breath of patients that is strongly associated with lung cancer and that could be an early signature of the illness.

“Breath analysis may be used in future as a screening test in high-risk people,” said Enole Boedeker, a research team member at the Schillerhoehe Hospital in Stuttgart, Germany. “A screening method for lung cancer does not exist yet,” Boedeker told The Telegraph.

Since the early 1970s, scientists have identified about 3,480 different volatile organic compounds in human breath. Some research groups have tried to analyse breath samples using chemical or electronic devices or sniffer dogs in search for compounds associated with lung cancer or tumours. But these efforts have yielded varying results — and no reliable diagnostic technique has emerged yet.

Boedeker and her colleagues worked with two German shepherd dogs, Bonnie and Kessie, Hector, a Labrador, and Benny, the two-year-old Australian shepherd dog, trained by Uwe Friedrich at a dog training centre.

Their study is the first to test if sniffer dogs can reliably distinguish between the breath samples of patients with lung cancer and those of healthy volunteers and patients with chronic obstructive pulmonary disease (COPD).

The researchers took breath samples from 220 volunteers who included patients with lung cancer, COPD, and healthy volunteers.

They found that if someone had lung cancer, the dogs correctly predicted it in 72 per cent. If someone did not have lung cancer, the dogs did not predict it in 90 per cent. “So the false negative outcome is 28 per cent, and a false positive outcome is 10 per cent,” Boedeker said.

“Dogs may help us find a volatile organic compound linked to lung cancer,” she said. The researchers said future studies should aim at identifying the compounds that the dogs are able to smell out in the exhaled breath of patients.

The German researchers said they were inspired by a 22-year-old research paper in a medical journal that recounted a tale of a woman who approached doctors to get a lesion on her skin examined after her dog began to pay special interest to the lesion.