Several labs have now confirmed that trained dogs can sniff prostate cancer in urine with accuracy exceeding 95%. This beats anything human technology can do. The latest biopsy technology, a quite unpleasant procedure, has a 33% false negative rate (fails to detect). Dogs can sniff other cancers as well. This may have great application in early detection of cancers.

The idea that dogs, with their super-sensitive sense of smell, could be used to detect cancer is not a new one, but until recently, it has been largely anecdotal. This appears to be about to change. A recent study was done in Italy using a pair of trained dogs. The dogs were originally trained in explosives detection. After retraining, they tested the dogs accuracy on a group of several hundred men, about half of whom had prostate cancer. The dogs got it right 97% of the time.

Now this wouldn’t necessarily count as a breakthrough if the medical profession had something equally accurate, but far from it. A state-of-the-art doppler guided 12 needle biopsy is unpleasant and expensive. It has a false negative rate of 33%, meaning 33% of those tested that actually had prostate cancer were pronounced free of it. Why? Prostate cancer frequently presents as many small tumors. If the needle pierces a tumor then it is detected, but if it happens to miss, it’s not detected. And this is about the best we have. The dogs win this one hands down. The dog’s 3% error rate is a factor of 10 better, and leaving a urine sample is so much easier than a #$%^&* prostate biopsy.

But, it is said, this could never be applied clinically. Why not? Perhaps each oncologist could be issued a dog in medical school. He could train with the dog, and then the dog would accompany him to work, on his rounds, and so on. It would certainly be healthy for the oncologist; they need a friendly companion in their daunting work.

Other Cancer Dogs Can Detect

What else can dogs detect? Breast cancer, ovarian cancer, melanoma, lung, and bladder cancer.

For bladder cancer, one test has the dogs at about 70% accuracy. This more or less matches the machines.

The ovarian cancer early detection results are very impressive, with one talented dog able to detect with 90% accuracy. This is a tough cancer to detect early.

Early detection of lung cancer is difficult as there are few symptoms. Dogs in one test got this one right with about 90% accuracy. In this case, the dogs sniff the breath of the patient.

Breast cancer? So far, this one seems to be resistant to the dog test, but given the success in the other cancers, perhaps with better training why not?

Many Cancers Are Curable if Caught Early

Cancers spread in stages. In latter stages, they migrate to other parts of the body. If they are caught while they are still small tumors, they can usually be eliminated.

Why are dogs so good at this?

We have around 5 million ‘smell’ receptors in our nose. Not bad, but a dog has over 200 million, 40 times as many.

Anyway, what is quite interesting is that researchers do not know how the dogs are doing it, or even what the dogs are actually smelling for that matter. When they figure this out, they can likely concoct an expensive machine to do the job. Perhaps it would look like this:

We would pay more for a friendly oncologist with a cancer-sniffing companion dog.