Cancer detection made easier by man’s best friend

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Health / Medicine

Imagine if there was something accessible, reliable and non-invasive to detect cancer before we even knew we had it. Sounds too good to be true, doesn’t it? But scientists have been working on just this. So, what exactly is this exciting cancer detector? Dogs!

Share the love: this post was written by science communication student Emma Giles.

A dog’s nose knows

We’ve heard of dogs being used for medical purposes before, such as guide dogs to assist the blind or seizure dogs to detect and respond to an upcoming seizure in their owner. But how could dogs possibly detect cancer, especially before we can?

The answer lies in dogs’ phenomenal ability to detect smells. Dogs rely on their sense of smell just as we rely on our sense of sight. Compared to humans, dogs are up to 10,000 times better at identifying smells. In fact, the percentage of a dog’s brain devoted to analysing scents is almost 40 times greater than a human’s. Clearly, dogs are the experts when it comes to scents.

Dogs are up 10,000 times better at identifying smells than humans.

Dogs are up 10,000 times better at identifying smells compared to humans. Image credit ‘gfpeck’ via Flickr.

But what does a dog’s ability to detect smells have to do with detecting cancer?

Well, it turns out that the initiation and development of cancer is associated with oxidative damage. Oxidative damage occurs when there is an over-accumulation of free radicals in our bodies. When this happens, we release volatile organic compounds into the environment through our breath, urine or sweat. With their incredible sense of smell, dogs are able to detect the odour of these compounds.

Dogs can be trained to respond in a particular way to these changes in smell, just as dogs are used at airports to detect suitcases containing illegal substances.

Amazingly, dogs even seem to be able to respond to these odours without training. There are several cases in which dogs became fixated on a part of their owner’s body, pawing it or acting distressed. This often led the owner to discover a small lump or bump, which, upon doctor examination, turned out to be cancerous.

With their cunning sense of smell, dogs have proven to be surprisingly accurate when differentiating between cancerous and non-cancerous samples. How accurate, you ask? Up to 98% accurate! When provided with urine samples from patients with prostate cancer, trained dogs are now able to detect the cancer more reliably than the currently-used blood test.

Early detection matters

With cancer, the earlier it’s discovered the better. This is because the more the cancer grows, the harder it is to treat. When left untreated, cancer can also spread to other parts of the body which complicates and prolongs the treatment process.

One of the biggest problems standing in the way of catching cancer early is that some cancers are extremely difficult to spot in the early stages. This means that some patients have to get really sick before their cancer is detected, and at this point their chances of survival have greatly decreased.

The good news is that dogs seem to be able to pick up on the cancerous chemicals in the very early stages of the disease. And because dogs are able to do this from simple samples of urine or blood, the process poses no harm or discomfort to either the patient or the animal.

Dog scans in the doctor’s office

To put this early detection into practice, researchers have suggested that dogs could be used to screen samples from patients following a routine exam. For example, if an abnormality appeared on a mammogram, dogs could aid in identifying which patients should proceed with a biopsy, which could increase the early detection rate of breast cancer.

In fact, researchers have already shown that dogs can do just that with incredible success rates. A study published in the Journal of Integrative Cancer Therapies found that if a woman had a tumor in her breast, the dogs were able to find it 88% of the time. Amazingly, if the dogs did find a tumor, 98% of the time it was cancerous.

While dogs probably won’t be in the doctor’s office anytime soon, researchers are continuing to present intriguing findings that the medical community is having trouble ignoring.

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