Man has been capitalizing on dogs’ remarkable sense of smell since ancient times, making use of them to detect illegal substances, missing people, explosives, wildlife, blood and even things like banned electronics in prisons. But it looks like we may have discovered yet another use of those soggy noses, as lately there has been an increasing amount of evidence to show that dogs could help us detect a wide variety of human cancers with remarkable accuracy. Last month, scientists declared that a German shepherd-mix named Frankie could detect thyroid cancer urine samples with an 88% success rate. A few days later two more German shepherds were trained to detect prostate cancer, and they produced accurate results more than 95% of the time.
At present prostate cancer — one of the leading causes of cancer death among men today —- is detected via a blood test that looks for a protein called prostate-specific antigen (PSA), which is produced by cells of the prostate gland. Normally this is present in paltry amounts in the blood, however, raised levels can point to the presence of prostate cancer. Nonetheless, other things like inflammation or a urine infection can as well trigger an increase in blood PSA, which is why it’s not reliable enough to be put to use on its own and need to be followed up with physical examinations and invasive tests like tissue biopsies.
Since there is apparently a clear need for superior prostate cancer tests, scientists are trying to find new and more accurate ways to pick up the condition, which is why some have turned their attention to world-renowned detectors: dogs. Past studies have proved that dogs have the ability to sniff out certain chemicals present in the urine of men with prostate cancer, therefore scientists from the Humanitas Clinical and Research Center, Milan, took the decision to take this further by testing out how accurate trained dogs could be.
For their investigation, they made use of two female German shepherd dogs who were trained to detect prostate cancer-specific compounds in urine samples. Both dogs were then tested out on 362 patients with prostate cancer and 540 controls who either had no cancer or nonprostatic tumors. They discovered that one dog spotted 100% of the prostate cancer samples and falsely identified just 7 negatives. The second dog accurately spotted 98.6% of positive samples and wrongly identified 13 non-prostate cancer samples as positive. Despite the fact that these results are impressive, the study has critical limitations, which means that we perhaps won’t see dogs in clinical settings just yet. At present, it’s ambiguous which cancerous chemicals the dogs are detecting, so we need to work this out first, and only then it will be possible to develop lab-based tests for them.
Besides, as the NHS points out, the study encompassed men who had already been diagnosed with prostate cancer, so more studies are required to see whether they can pick up cases that have not yet been diagnosed, or to monitor men with high PSA but negative biopsies.