Add another capability to what dogs can do with their amazing senses of smell: Not only can they detect breast cancer and allergens, but according to a new study, dogs can also sniff out prostate cancer compounds in urine.
Researchers from Tenon Hospital in Paris announced at an American Urological Association meeting this week that dogs can be trained to detect the odor of unique chemicals that are released into urine from prostate tumors.
This test could be more effective than the controversial prostate-specific antigen (PSA) blood test at identifying men most at risk for prostate cancer.
According to a New England Journal of Medicine study, the PSA test results in too many false positives and is thus associated with a high risk of overdiagnosis. For every life the test ends up saving, 47 men undergo unnecessary surgery and radiation treatments.
Dogs may eventually make the PSA test obsolete. Along with prostate cancer, many other tumors release chemicals into human urine that can be detected by dogs. Renal & Urology News reports that earlier studies have shown promising results using dogs to detect bladder and breast cancer by smelling urine samples. One British study found that trained dogs had a 41-percent success rate in sniffing out bladder cancer in urine samples.
For the prostate cancer study, Dr. Jean-Nicolas Cornu and his colleagues spent a year training a Belgian Malinois — a shepherd breed whose sharp sniffing skills have been used to detect other cancers as well as bombs — to differentiate urine samples from men with confirmed prostate cancer to specimens from healthy subjects.
The dog’s nose was then put to the test with five urine samples — one from a prostate cancer patient and the others from healthy men. The dog successfully sniffed out the prostate cancer patient’s urine 63 out of 66 times. There were three false positives and no false negatives, meaning the dog identified all the prostate cancer patient samples, but misidentified three samples from healthy subjects.
“These results suggest that VOCs [volatile organic compounds] produced by cancer cells can be detected in urine samples,” the researchers concluded, according to Renal & Urology News. “Identification of these substances could lead to a highly specific screening tool for prostate cancer.”
While signs of prostate cancer can turn up in urine tests, Cornu told Business Week that the tests miss some cases. Some types of molecules give a distinct odor to urine, “but today there is no means to screen odors from urine and separate them,” he said, or to link them to cancer.
Cornu admitted he doesn’t understand exactly what the dogs are sniffing for. “The dogs are certainly recognizing the odor of a molecule that is produced by cancer cells,” he told Business Week, “[but] we do not know what this molecule is, and the dog cannot tell us.”
Once researchers can identify the specific molecule, they will develop an electronic “nose” that will replace fur-legged sniffers.
PHOTO: commons.wikimedia.org
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