Dogs Detect Cancer
Honestly, sometimes it's hard to resist laughing when reviewing the health news, even if the subject involves something unsnickerable. Take the latest announcement from Schillerhoehe Hospital in Germany proclaiming that their research shows dogs do a darned good job of identifying people who have lung tumors just by sniffing them.1 To test the canine's astuteness as cancer-screeners, the researchers asked 220 people, some of whom had lung cancer, to breathe into test tubes filled with fleece. Four dogs stood on alert until their trainer yelled "Cancer -- Go!" Then the dogs would run and sniff the test tubes. If they detected cancer, the dogs sat down and put their nose on the test tube. Every time they made a correct identification, they got a treat, and hopefully, a belly rub.
Apparently, the dogs correctly identified cancer cases 71 percent of the time. Even better, in another set of tests, they correctly identified 371 out of 400 non-cancer samples, garnering a 93 percent score. These dogs did not go to medical school. They did not spend hundreds of thousands of dollars on fancy CT equipment in order to make their diagnoses. Rather, they attended obedience school for about 11 weeks. Their trainer says that their performance improved over the course of their study, and he assumes that with more training, the accuracy rate would continue to get better.
Mind you, by the way, that the four dogs involved weren't even Border Collies or Poodles, the two smartest breeds. As it turns out, smarts don't matter. Rather, the canine diagnosticians were two German shepherds, an Australian shepherd and one Labrador. These breeds have remarkable scent-detecting abilities. Makes you wonder why they didn't try a bloodhound, though.
The researchers can't figure out exactly what it is that the dogs are smelling that allows them to identify the cancer. If they could identify the chemical that the dogs detect only in cancer victims, they might be a whole lot better at finding lung cancer at an earlier stage, saving lives in the process.
Apparently, cancer introduces specific VOCs -- or volatile organic compounds -- into the breath, and those VOCs, if present, leave traces in the test tubes. Human breath typically contains about 4000 different VOCs, so finding the cancer-related one is no easy trick. Dr. Thorston Walles, who led the study, explains, "In the breath of patients with lung cancer, there are likely to be different chemicals to normal breath samples and the dogs' keen sense of smell can detect this difference at an early stage of the disease. Our results confirm the presence of a stable marker for lung cancer. This is a big step forward in the diagnosis of lung cancer, but we still need to precisely identify the compounds observed in the exhaled breath of patients."2
Lung cancer typically shows few early symptoms, making it difficult to diagnose until the victim moves into later, deadly stages.3 While studies have shown that CT scans of heavy smokers performed regularly cut mortality risk by 20 percent, the sad truth is that those scans result in a high rate of false positives -- not to mention the fact that CT scans themselves can cause cancer. Give someone enough CT scans and you'll have a self-fulfilling diagnosis. But back to false positives. About one in four cancer-free patients undergoing a CT scan for lung cancer will get a false positive diagnosis. And once a patient gets that positive diagnosis, they likely will be exposed to dangerous and expensive treatments to cure the disease they don't have. Dogs, on the other hand, have only a seven percent false positive rate -- even with limited training. And dogs, unlike CT scans, don't pummel your body with horrific amounts of radiation.
Past studies have tested dogs for accuracy in finding other diseases. Canines performed better than PSA tests in detecting prostate cancer in preliminary trials, while producing fewer false positives.4 They also have a remarkable ability to sense oncoming diabetic attacks. And, recent research from Japan found that dogs detect colon cancer with a 90 percent accuracy rate working with either stool or breath samples. That's close to the colonoscopy accuracy rate. Scalpel or snout -- which would you prefer?
Not surprisingly, the medical community hopes that the canine talent will translate into the manufacture of something that can be used for diagnostic purposes.
Says Dr. Gary K. Beauchamp, who directs the Monell Chemical Senses Center in Philadelphia, "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." His colleague, Dr. Suresh S. Ramalingam, MD, of the Emory University Winship Cancer Institute, adds, "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…We need to find out what the dogs are sniffing so we can do it in a more scientific manner." That sure sounds like a call to build a device or manufacture a chemical test or come up with something that most likely will be more expensive than a dog, more hazardous, and more profitable to the medical community.
It's interesting to note that while scientists scramble to create more accurate tests or devices, dogs already have an accuracy rate between 70 and 90 percent, and the trainers say that can be improved by training the dogs better and longer. But training Spot to be spot-on as a diagnostician perhaps insults the medical intelligence, even as an interim measure -- though it's safe, fast, pretty darned accurate, and far more fun than the CT machine.
"Paging Dr. Fido! Paging, Dr Fido!"
1 "Dogs can be trained to sniff out cancer." 17 August 2011. Times of India. 17 August 2011. < http://timesofindia.indiatimes.com/home/science/Dogs-can-be-trained-to-sniff-out-cancer/articleshow/9653979.cms>
2 Park, Alice. "A New Way to Detect Lung Cancer? Dogs Can Sniff it Out." 18 August 2011. Time Healthland. 18 August 2011. < http://healthland.time.com/2011/08/18/a-new-way-to-detect-lung-cancer-dogs-can-sniff-it-out/>
3 Goodman, Linda. "Dogs Sniff Out Lung Cancer in Humans." 17 August 2011. WebMD. 17 August 2011. < http://www.webmd.com/lung-cancer/news/20110817/dogs-use-their-noses-to-detect-lung-cancer>
4 Laino, Charlene. "Dogs Sniff Out Prostate Cancer." 2 June 2010. WebMD. 18 June 2010. < http://www.webmd.com/prostate-cancer/news/20100602/dogs-sniff-out-prostate-cancer>