Dogs Have A Nose For Detecting Cancer

Cancer researchers are finally going to the dogs.  After decades of anecdotal evidence, studies now confirm that canines' keen sense of smell can detect cancer in humans. The challenge for scientists is to figure out how to harness dogs' ability to sniff out cancer to detect the disease in its earliest stages.

Over decades, many stories emerged about dogs discovering cancer in their owners.  Scientists mostly dismissed the accounts because there was no research to validate the episodes.  However, a growing number of studies have verified that trained dogs can indeed spot many types of cancer.

That finding doesn't surprise dog owners with first-hand experience with the phenomenon.  For instance, a San Antonio woman noticed her golden retriever began drooping his head in her lap.  He repeated this every day.  The women went for a check up and was diagnosed with kidney cancer.

A Rochester, Minnesota, woman was studying for a university test when her golden retriever-St. Bernard mix-breed began nosing at her left side.  The dog became agitated.  When the woman wiped away the dog's slobber, she felt a lump.  She was later diagnosed with breast cancer.

A Hollywood actress reported a similar experience with her German Shepherd.  She discovered that she had breast cancer too.  So what enables a dog to be able to sense the disease?  The answer is dog gone simple.  Canines have a nose for it.

Dogs have about 300 million odor receptors, compared to about six million for humans.  They also are equipped with a second smelling apparatus, the vomeronasal organ.  It has sensors near the back of the nasal cavity that detect certain chemical substances.  But dogs have another advantage.

The section of the dog's brain devoted to analyzing smells is 40 times larger than a human's brain capacity.  By some estimates, scientists claim that the dog's sense of smell may by 10,000 to 100,000 times more sensitive than we lowly human beings.

Law enforcement officers may have been the first to employ dogs to sniff out illegal paraphernalia.  They trained canines to find hidden drugs and contraband using their sense of smell. Dogs have been deployed by security and the military from airports to war zones to detect concealed bombs.

A few years ago scientists began investigating another application: using dogs to detect cancer in humans. Oncologists generally agree that cancer tumors emit unique odors, which cannot be recognized by humans or even the latest detection technology.  Could dogs smell cancer?

That question triggered a series of studies in the United States and abroad.  Among the most exciting was an Italian study which showed that two German Shepherds analyzing urine samples from nearly 900 patients correctly identified cancerous specimens with almost 100 percent accuracy.

The findings generated headlines but also skepticism among some scientists, who can be stubbornly resistant to new ideas.  They needed more convincing.  Veterinarians came to the rescue.  The Penn Vet Working Dog Center the University of Pennsylvania demonstrated the power of dog's nose.

Dogs at the center were trained using what they refer to as a "scent wheel"--a round table hung with bread-loaf sized, perforated steel boxes around the perimeter.  The boxes are stuffed with odor samples.  A few boxes include cancerous urine, tissue and blood samples.

If the dog smells cancer, it sits in front of the box.  As part of the training, researchers put decoy boxes with blood samples that are noncancerous.  After intensive training, the dogs learn to spot cancer with surprising accuracy.  The demonstration convinced even some skeptics.

Other trials have quantified that dogs can be trained to sniff urine, blood and even biological samples to detect a range of cancers, including bladder, breast, colorectal, lung, ovarian, prostate and skin.  Dogs can't identify the particular cancer, but do smell the presence of the disease.

Scientists are warming to the idea of training dogs to sniff cancer screening samples.  However, the humans in the white lab coats consider it a logistical nightmare to train thousands of dogs.  But what if a machine that could mimic a dog's sense of smell?  There must be an app for that, right?

The Monell Chemical Senses Center, a nonprofit that collaborates with the University of Pennsylvania, has begun to tackle the issue of designing a computer chip with enough capacity to match the canine's olfactory ability.  Scientists admit it it may be an impossible feat.

However, there are devices (i.e. electronic noses) that are already used in breath tests administered by law enforcement officers.  Other devices have been engineered to detect one particular smell.  But to be effective, the new technology must be able to distinguish hundreds of different smells.

In the future dogs, perhaps will work along side instrument-based cancer detectors. This approach may yield earlier detection for some cancers.   If it does, dogs will no longer be just a human's best friend.  Canines could be a humanity's best chance for surviving cancer.