Man's best friend, the dog, may also be a lifesaver. New research finds that super trained pups are able to sniff out lung cancer in a human's breath, making detection easier and earlier for doctors. This will allow them to treat the ailment earlier and save more lives. Nice.
The new study found that 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 down to about 7%.
In his study, 220 volunteers (110 who were healthy, 60 who had lung cancer, and 50 with chronic obstructive pulmonary disease) were asked to exhale into a glass tube filled with fleece. The tubes were mixed up so neither the dogs' handlers nor two observers who placed the samples on the floor in front of the dogs knew the status of the person they were from, to avoid inadvertently giving the dogs clues about what they should find.
The dogs were presented with five tubes at a time. Only one contained a sample from a person with cancer and dogs were trained to lie down and put their nose to the tube if they detected lung cancer.
The dogs appeared to be able to accurately identify the samples from cancer patients, even when they were in very early stages of the disease. And they were able to pick up the scent despite competing odors of cigarette smoke or food on a person's breath.
Suresh S. Ramalingam, MD, associate professor and director of the lung program at Emory University's Winship Cancer Institute in Atlanta is excited about the idea:
"This is the holy grail. The whole field is focused on using something that's readily available that does not involve an expensive surgery or scan that would allow us to find early cancers."
It also seems dogs can detect other types of deadly cancers based on past studies. Doctors have previously reported cases in which dogs have alerted their owners to undiagnosed skin, breast, and lung cancers by repeatedly pawing or nosing an affected body part. Some dogs have even been trained to smell low blood sugar levels in people who have diabetes.
A study from 2004 found that dogs correctly identified bladder cancer an average of about 40% of the time, a rate that was better than the 14% accuracy that could be expected by chance, but was lower than available tests.
Earlier this year even, Japan reported that dogs could detect the presence of colon cancer in human breath and stool samples with nearly 90% accuracy, a success rate only slightly lower than colonoscopy.
Thorsten Walles, MD, a lung surgeon at Schillerhoehe Hospital in Gerlingen, Germany continues:
"The surprising result of our study is the very high specificity of our dogs to identify lung cancer. It even surpasses the combination of chest computed tomography (CT) scan and bronchoscopy, which is an invasive procedure that needs some form of anesthesia."
Researchers think dogs and other animals are able to smell disease by picking up on minute changes in some of the 4.000 breath compounds called volatile organic compounds (VOCs) that comprise chemical signatures in the body.
Gary K. Beauchamp, PhD, director of the Monell Chemical Senses Center in Philadelphia explains:
"It's not just how sensitive their nose is. It's how they process this into a recognition pattern. 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. The dogs show that it can be done. We need to find out what the dogs are sniffing so we can do it in a more scientific manner."
Written by Sy Kraft