Everyone knows that dogs have a phenomenal sense of smell. Measurements have shown that it is 10,000 to 100,000 times better than the human sense of smell. Now researchers at Amersham Hospital, northwest of London, have shown that dogs can be trained to smell cancer.
John Church, a retired surgeon, thought up the study after reading about a border collie-Doberman pinscher mix that kept sniffing at a mole on its owner's leg and even tried to bite it off. The owner finally consulted a dermatologist (skin specialist), who discovered that the mole was cancerous.
The new study involved six dogs--three cocker spaniels, one papillon, one Labrador retriever, and a mutt. The dogs were trained over a period of seven months to tell the difference between urine from healthy people and urine from people who had bladder cancer. The bladder is a hollow, elastic organ that stores urine.
When the dogs were tested with new urine samples after their training period, two cocker spaniels, Tangle and Biddy, correctly sniffed out cancer 56 percent of the time. Overall, the dogs had a 41 percent success rate. That number is far higher than chance, which yields a correct response only 14 percent of the time. The researchers believe that the dogs were able to sense some type of unidentified chemical that bladder cancer cells release into urine.
Some doctors have expressed disappointment with the study. One doctor said he expected the dogs to perform even better. A useful medical test must be better than 41 percent accurate.
The study is only the first of its kind, though, and the dogs may improve with training. In addition, researchers may one day identify the chemical signal the dogs can detect in urine and use it as a target molecule that machines--"electronic noses"--can spot.
Church says that the study's best result was a surprise diagnosis. Thirty-six bladder-cancer patients and 108 healthy volunteers provided urine for the study. All six dogs indicated that one "healthy" sample came from a cancer patient. The man who provided the sample was tested and found to have a kidney tumor. "As you can guess," Church told The New York Times, "we were cock-a-hoop about that."
|
Search Tucson Medical
