In a study published in the European Respiratory Journal, scientists from Schillerhoehe Hospital in Germany have discovered that dogs' enhanced sense of smell is able to detect lung cancer in breath samples from patients.

Four dogs participated in the study: two German shepherds, one Australian shepherd, and one Labrador retriever. The dogs sniffed 220 test tubes containing breath samples from various patients, 100 of which were from patients with lung cancer.

The dogs were trained to sniff the tubes and when they detected the presence of lung cancer, to lie down and touch the test tube with their noses. The dogs successfully identified 71 lung cancer cases out of the 100. The dogs could detect even people with early stages of lung cancer, and could also tell the difference between lung cancer and chronic obstructive pulmonary disease (COPD).

The research suggests that there is a detectable compound in the breath of patients with lung cancer that indicates the presence of the disease, and that in the future could be used to detect and treat lung cancer early. Scientists hope that these volatile organic compounds (VOCs) in the breath of patients will eventually play a role in early detection of cancer, but current technology is not able to pinpoint VOCs specifically tied to lung cancer.

However, the fact that the sniffer dogs were able to detect lung cancer, even in the presence of interference from other conditions such as COPD as well as tobacco smoke, points to the presence of a stable marker for lung cancer that may eventually be isolated. Researchers told WebMD that the dogs' accuracy surpassed even that of combined CT scan and bronchoscopy.

Ultimately, the goal will be to develop a screening test that can detect the presence of VOCs associated with lung cancer, which will allow doctors to detect early stages of cancer before it can be found by other tests. This could allow far earlier treatment of the cancer. This would be a huge step forward in public health, as lung cancer is the most common cause of death from cancer worldwide and is the second most common cancer in Europe and the United States.

The researchers lamented that unfortunately, "dogs cannot communicate the biochemistry of the scent of cancer!" However, dogs may have provided an important step towards isolating early markers for the disease. Other research has already suggested that dogs may be able to play a role in identifying other types of cancer. For instance, in a Japanese study earlier this year, dogs were able to sniff out early stage colon cancer from patients' breath and stool samples with over 90% accuracy.