A trained scent dog has proved successful in sniffing out thyroid cancer in people who had not yet been diagnosed, U.S. researchers are reporting.

A German shepherd-mix named Frankie, taking a sniff of urine samples from patients, was 88.2 percent successful in identifying whether the samples showed thyroid cancer or were benign, they said.

Dogs are well known for their incredible sense of smell, with noses that contain more than 220 million odor sensors, making them thousands of times more sensitive than a human nose and its mere 5 million olfactory sensors.

"Current diagnostic procedures for thyroid cancer often yield uncertain results, leading to recurrent medical procedures and a large number of thyroid surgeries performed unnecessarily," said Dr. Donald Bodenner, head of endocrine oncology at the University of Arkansas in Little Rock.

These procedures typically involve a fine-needle biopsy of suspicious thyroid nodules to collect cells and analyze them for malignancy.

It's a simple procedure but never completely accurate, Bondenner points out, and sometimes requires additional biopsies or sometimes other painful or expensive procedures.

Frankie, as trained by the Arkansas researchers, could identify the presence of thyroid cancer with a success rate only slightly less than that of a needle biopsy but with the advantage of offering an inexpensive and non-invasive alternative, Bondenner says.

The dog can recognize the presence of cancer because the multiplying cells have an identifiable chemistry and release certain volatile organic compounds that end up in urine, the researchers explain.

They reported their results at the 97th annual meeting of the Endrocrine Society in San Diego.

Although Bodenner says he is not yet establishing patient treatment decisions based on the dog's ability, confining it for the moment to a research context, he says he's encouraged by the animal's diagnostic accuracy, and sees a day when the technique may take a rightful place in a doctor's diagnostic arsenal.

"Scent-trained canines could be used by physicians to detect the presence of thyroid cancer at an early stage and to avoid surgery when unwarranted," he says.

Frankie was trained to recognize the disease by smell using thyroid tissue taken from a number of patients diagnosed with thyroid cancer, said study co-author Arny Ferrando.

"Frankie is the first dog trained to differentiate benign thyroid disease from thyroid cancer by smelling a person's urine," he said.

One thyroid cancer expert said the results with Frankie are encouraging.

"Dogs have been known to detect multiple cancers -- from melanomas to breast cancers and lung cancer, just to name a few," said Dr. Maria Pena, an endocrinologist at Syosset Hospital in Syosset, N.Y. "Now this same concept is being applied to the detection of thyroid cancer."