Long time blog readers may remember the post we did last year detailing how dogs use their keen sense of smell to detect prostate cancer. Now German researchers have found that certain breeds of highly trained dogs are able sniff out lung cancer in human breath too. And their accuracy rate is higher than traditional diagnostic procedures.

This is good news for those with early stage lung cancer which has few symptoms, making it difficult for doctors to catch it early while it's still treatable.The current screening procedure for those at high risk for lung cancer is computed tomography (CT) scans which can cut the risk of dying of the disease by 20%. But that test has caused controversy because it falsely detects cancer in about one out of four people, leading to further invasive procedures.

Dogs have impressive accuracy

The four trained dogs -- two German shepherds, an Australian shepherd, and a Labrador retriever -- correctly identified cancer in 71 of 100 samples from lung cancer patients. They also ruled out cancer in 372 out of 400 samples that were known not to have cancer, giving them a very low rate of false positives, about 7%.
"The surprising result of our study is the very high specificity of our dogs to identify lung cancer," says study researcher Thorsten Walles, MD, a lung surgeon at Schillerhoehe Hospital in Gerlingen, Germany.

"It even surpasses the combination of chest computed tomography (CT) scan and bronchoscopy, which is an invasive procedure that needs some form of anesthesia," said Walles.

How dogs detect cancer

Researchers think dogs and other animals are able to smell disease by detecting minute changes in volatile organic compounds (VOCs) that comprise chemical signatures in the body. As many as 4,000 different VOCs, for example, have been identified in human breath.

A dog's sense of smell has been estimated to be 100 to 1,000 times more powerful than a human's, says Gary K. Beauchamp, PhD, director of the Monell Chemical Senses Center in Philadelphia.

"It's not just how sensitive their nose is. It's how they process this into a recognition pattern," Beauchamp says. "The reason dogs can do this is that they're recognizing a complex picture, and that's the big trick, to find out how to mimic that in some sort of device that could be useful for diagnostic purposes in human disease."

And since other research with dogs has shown that they can detect other cancers and even smell low blood sugar levels, this field of research has wide ranging implications.

Source:

Medscape