A new urine-based sniff test “might help reduce the number of unnecessary biopsies”, says lead author Dr. Gianluigi Taverna. Highly trained dogs detected prostate cancer with 98% accuracy according to a study presented May 18th.
“This study gives us a standardized method of diagnosis that is reproducible, low cost and non-invasive,” said lead author Dr. Gianluigi Taverna, Chief of the Prostatic Diseases Unit at the Humanitas Research Hospital in Milan, Italy, “Using dogs to recognize prostate cancer might help reduce the number of unnecessary biopsies and better pinpoint patients at high risk for the disease”.
Researchers in Italy enrolled 902 participants and divided them into two main groups: 362 men with prostate cancer, ranging from very-low risk tumors to metastatic disease, and a control group made up of 540 men and women in generally good health or affected by other types of cancer or non-tumor related diseases. All participants provided urine samples.
Two three-year old, female German Shepherds (previously having worked as explosive-detection dogs) named Zoe and Liu were trained for about five months at the Italian Ministry of Defense’s Military Veterinary Center in Grosseto using the positive reinforcement “clicker method” and “imprinting,” during which the dogs learn to distinguish certain distinctive scents.
During the training, 200 urine samples from the prostate cancer group and 230 samples from the control group were analyzed. The dogs were taught to recognize prostate cancer-specific volatile organic compounds (VOCs) in the samples. (According to the team, new urine samples were provided for the evaluation phase.)
The dogs were instructed to sit in front of each sample where they detected the prostate cancer VOC. None of the team members knew which samples were which, except the chief medical veterinary surgeon, who observed from outside the room. The dogs were rewarded when correct identifications were verified.
Dog 1 achieved 100 percent accuracy in detecting samples from prostate cancer patients and 98 percent accuracy in eliminating samples that did not come from a prostate cancer patient. Dog 2 was close, with 98.6 percent accuracy in detecting prostate cancer and 96.4 percent accuracy in eliminating those that didn’t have the disease. Overall, the dogs had 16 false positives and four false negatives.
Though the high accuracy displayed by the dogs is encouraging, they are not about to replace human doctors, Taverna pointed out. Plenty of other information, like tumor stage and size, and the age of the patient – none of which the dogs can detect – go into determining treatment, he noted.
Dog-detection is a technique that “needs to be combined with other, common diagnostic tools (PSA, biopsy, MRI, etc.),” Taverna said, his team wants “to expand on our current study by converting the chemicals detected by the dogs into gas chromatography-mass spectrometry so the process can be duplicated by machine. “ They are working to figure out just what chemicals it is that the dogs are detecting.
While humans have roughly five million olfactory cells (receptors that detect different odors) in their noses, dogs have about 200 MILLION!! Woof to that!
It is estimated that 233,000 men in the US will be diagnosed with prostate cancer this year. Although current screening methods for the disease – such as digital rectal exams – aid early detection, they are not always accurate. But with the help of “man’s best friend,” the Dog-Detection technique could be in the cards.
Just when you thought dogs couldn’t be more giving of unconditional love … now they are helping to find and fight prostate cancer in humans. Absolutely amazing creatures!
Bark about it!