The idea that dogs might be able to smell cancer in people has been around for a while, but various studies have recently started to provide more robust evidence to back these reports up. Now, the National Health Service (NHS) in the U.K. has approved the use of cancer-detecting dogs in trials to test their ability to sniff out prostate cancer. Initial studies have found that they can successfully detect this cancer in 93% of cases.
“Over the years, there have been many anecdotal reports suggesting that dogs may be able to detect cancer based on the tumor’s odor,” explained Iqbal Anjum, a consultant urologist at Milton Keynes University Hospital, where the trials are set to take place. “It is assumed that volatile molecules associated with the tumor would be released into the person’s urine, making samples easy to collect and test.”
The current test for prostate cancer in men over 50 is called the Prostate-Specific Antigen (PSA) test. This is a blood test that examines levels of a particular molecule secreted by the prostate that is often – though not always – elevated in those who have prostate cancer.
While it is estimated that one in eight men will develop the disease, the PSA blood test is thought to fail to detect the cancer in 20% of those who have it, and gives many false positive results. This means that many men who do not have the disease are often referred for invasive biopsies.
It is hoped that using dogs as a second level in a screening process that will first involve the PSA test, doctors will be able to massively ramp up their accuracy of testing for the cancer, reducing the number of unnecessary biopsies. The dogs are trained to identify the cancer by sniffing a sample of urine taken from the patient. It is thought that the dogs' extraordinary sense of smell – able to detect parts per trillion – allows them to detect certain “volatiles” that travel from the prostate cancer into the urine.
“Britain has one of the worst rates of early cancer detection in Europe,” explained Dr Claire Guest, who founded the charity Medical Detection Dogs, who will be carrying out the trials. “The NHS needs to be bolder about introducing new innovative methods to detect cancer in its early stages. Our dogs have higher rates of reliability than most of the existing tests. We should not be turning our backs on these highly sensitive bio-detectors just because they have furry coats.”