Dogs able to sniff out cancerous melanoma
"Could I have prevented this from happening to me?" a 55 year-old man writes. For many years he had been aware of a suspicious mole on his leg. But he had been reassured by a dermatologist that it was a benign mole. The wrong diagnosis. Now this patient is dying from a malignant melanoma that has spread to other organs. Could George, the dog, have saved his life?
The man's letter reminded me of an incredible story published by the Medical Post in June 1997. George, a lovable grey-haired schnauzer had been trained to sniff out explosives. But then his career was changed by Dr. Armand Cognetta, a dermatologist in Tallahassee, Fla.
Cognetta has written about the most effective ways of treating melanomas. That hand-held microscopes can be used to examine moles and make an earlier diagnosis. But he reports, even so, doctors only diagnose 80% of melanomas in time.
One night while driving home he turned on the car radio He listened, fascinated, to a news report Local police were searching for a body at the bottom of a lake. But they were not using divers or hooks to discover the body. Rather, a trained dog was standing in the bow of a boat sniffing the air.
This rang a bell in Cognetta's mind. He began searching medical literature and finally discovered what he wanted. In 1989, the British Journal Lancet published an intriguing medical account from King's College Hospital in London.
A female half Border collie, half Doberman, had turned doctor. The dog had alerted a 44 year old woman to a lesion on her thigh. The woman reported that the dog kept sniffing at this lesion, but it ignored other moles. In fact, the dog even attempted to bite off the offending mole when she was wearing shorts.
The woman consulted her doctor and the mole was excised. The diagnosis? Malignant melanoma.
Cognetta decided to conduct his own experiment. He wanted to determine if malignant melanomas emit unique odors that cannot be detected by humans, but can be recognized by dogs with their well-developed rhinecephalon.
A dog's nose has about 220 million cells associated with the sense of smell. Humans have a mere five million.
Dr. Cognetta needed some professional help So he enlisted the support of Duane Pickel who had worked with dogs for 30 years. Picket had trained dogs to find anything from land mines in Vietnam to drugs and smuggled wildlife.
He told Cognetta: A dog can be trained to find anything you want it to find."
The doctor obtained tissue samples from melanomas from two re search institutes and the Tallahassee Memorial Regional Medical Center prodded equipment to preserve the delicate tissue.
George was then trained to find the tube containing melanoma samples. Eventually he was trained to discover the melanoma sample when placed in one of 10 holes in a large rectangular box George was right 99% of the time.
But what about patients? Kim Edwards, a nurse at Tallahassee Memorial Hospital, agreed to join the study. Edwards was interested because she had a family history of skin cancer.
How does a dog examine a patient? Cognetta and Pickel designed a table close to the ground shaped like a gingerbread man, one on which Edwards could lie while George sniffed her body. Forty tests were conducted. Dozens of bandages were placed on Edwards' body, but only one contained the live melanoma sample.
George discovered the cancer sample almost 10096 of the time.
The dog's diagnostic ability was then tested on other parents without the use of tissue samples. During a l0 month period, seven patients agreed to have George sniff them for skin cancer.
The first parent was placed on the examination table. Pickel then said to George, "Show me." George sniffed over her body, sat down, lifted his paw and tapped the mole. The mole was removed. Again the diagnosis was malignant melanoma.
George subsequently diagnosed skin cancer in four of seven patients suspected of having the disease.
Cognetta agrees that having dogs sniff your body for melanomas is hardly ideal. But since we are far from winning the war on melanomas, it's prudent to look at all possible diagnostic strategies.
Preventing melanoma is the best approach. This means using sunscreen and covering up if you're in the sun for long periods. Check your skin for moles at regular intervals. I look for changes in size, shape, color bleeding, itching or tenderness.
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