Dogs can detect lung cancer, study concludes
According to a recent scientific paper published in the Aug. 18, 2011 issue of the European Respiratory Journal, "It must be assumed, that a robust and specific volatile organic compound (VOC or pattern) is present in the breath of patients with lung cancer." Tumors typically generate VOCs, which dogs are able to smell. In fact, in this study, dogs had a 71 percent success rate at accurately detecting cancer.
The study, conducted from December 2009 to April 2010, included two German Shepherds, an Australian Shepherd and a Labrador Retriever. Ultimately, there were 220 patients who were in one of three groups: those in good health (110 people); those with lung cancer (60) and those with chronic obstructive pulmonary disease (50). People with other cancers (suspected or confirmed) were excluded.
It is theorized that lung cancer generates different chemicals in the breath than those found in normal breath samples, and the dogs, according to Walles, were able to note the difference early on in the disease. He says the results indicate evidence of a stable marker for lung cancer.
And that will help researchers begin to analyze breath samples with the aim of building a diagnostic test for those suffering from lung cancer. But there is much work left to be done. In fact, researchers will next need to rule out the possibility that the dogs were picking up smells from other common chemicals in the breath of cancer patients, like certain medications. And they will need to isolate that chemical market.
While the dog's boasted a success rate for detecting cancer 71 percent of the time; they were not usually thrown off by chemicals associated with COPD or smoking, Walles says.
But the tube-test screening presented challenges, Walles says.
"We had to re-start our dog training because we learned that the dogs were able to memorize breath samples of patients. We had to make sure that each dog was exposed to each breath sample only once during the more than six-month-long training period and testing. Given the large number of samples (>200) and the complex composition of breath samples containing probably more than 3,000 different chemical compounds this was startling," he says.
Further research, according to Walles, will likely investigate whether the dogs are able to detect other cancers. In the future, he says his team wants to work with other groups experienced in sensor technologies to advance research in finding a molecular target for lung cancer screening.