Tumor sniffers: training dogs to detect cancer

A dog is a man’s best friend. Aside from this role, however, dogs also act as nurses to people with disabilities. So why not dogs detecting health problems?

Dogs have one of the most sensitive sense of smell among animals. But can they be trained to smell the scent of cancer accurately? Two research centers claim they have achieved this.

Pine Street Clinic, California

(Source: New York Times):

The clinic claims it has successfully trained 5 cancer-sniffing dogs consisting of three Labradors and two Portuguese water dogs. These dogs are supposedly able to detect lung cancer by sniffing the breath of the patients – with 99 percent accuracy! Their report was met with amazement (astounding!) as well as scepticism (too good to be true!).

According to Dr. Ted Gansler, director of medical content in health information for the American Cancer Society:

“It’s biologically plausible, but there has to be a lot more study and confirmation of effectiveness.”

The trained dogs were from different sources: from owners as well as from Guide Dogs for the Blind. The training was similar to that when dogs are trained to detect bombs, as follows:

The clinic collected breath samples in plastic tubes filled with polypropylene wool from 55 people just after biopsies found lung cancer and from 31 patients with breast cancer, as well as from 83 healthy volunteers. The tubes were numbered, and then placed in plastic boxes and presented to the dogs, five at a time. If the dog smelled cancer, it was supposed to sit.For breath from lung cancer patients, Mr. McCulloch reported, the dogs correctly sat 564 times and incorrectly 10 times.

Cancer and Bio-detection Dogs, UK

(Source: National Geographic News)

This non-profit cancer organization trains dogs to detect bladder cancer by sniffing urine samples. Here is how the dogs were trained: 8 urine samples were placed in a carousel and the dog has to sniff out the sample from a cancerous bladder. When it detects the cancerous sample successfully, the dog gets a food treat as a reward.

According to Claire Guest, head of the cancer center:

“Now that we know that dogs are able to detect human disease by its odor, and that different diseases have different odors, the potential is just incredible to help individuals with life-threatening conditions but also to have new ways of looking at diagnosis of life-threatening diseases such as cancer.”

So how do these amazing animals do it?

It is a known fact that tumors release very small amounts of compounds (e.g. alkanes and benzene derivatives) which are not in healthy tissues. The dogs highly sensitive olfactory nerves seem to be able to detect minute amounts (in parts-per-billion!) of these abnormal compounds in the breath, skin, and urine of cancer victims.

According to dog trainer Rob Harris

“Dogs have a highly-developed sense of smell. Their nose is in use every day. We just use that part of their nose to help us identify the odor of cancer.”

Also check out: dogs can detect (and therefore warn of) a hypoglycemic attack in patients with diabetes!

Photo credit: stock.xchng