Scent-trained dog detects thyroid cancer in human urine samples
A trained scent dog accurately identified whether patients' urine samples indicated thyroid cancer or were benign (noncancerous) 88.2% of the time, according to a new study. These findings were presented at ENDO 2015: The 97th Annual Meeting & Expo, in San Diego, California.
"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 senior investigator, Donald Bodenner, MD, PhD, chief of endocrine oncology at the University of Arkansas for Medical Sciences (UAMS) in Little Rock.
"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," Bodenner commented.
Although Bodenner is not yet basing patient treatment decisions on the canine technique, he said the dog's diagnostic accuracy is only slightly less than that of fine-needle aspiration biopsy, the method generally used first to test thyroid nodules for cancer. Canine scent detection has the advantages of being noninvasive and inexpensive, he said.
Bodenner's colleague at UAMS and a study coauthor, Arny Ferrando, PhD, previously imprinted (scent-trained) a rescued male German Shepherd-mix named Frankie to recognize the smell of cancer in thyroid tissue obtained from multiple patients. Ferrando, who noted that dogs have at least 10 times more smell receptors than humans, said, "Frankie is the first dog trained to differentiate benign thyroid disease from thyroid cancer by smelling a person's urine."
In this study, 34 patients provided a urine sample at their first visit to the university thyroid clinic before undergoing biopsy of suspicious thyroid nodules and surgery. The surgical pathology resulted in a diagnosis of cancer in 15 patients and benign thyroid disease in 19. A gloved dog handler presented the urine samples to Frankie one at a time to sniff. Neither the dog handler nor the study coordinator, who recorded the dog's responses after the handler announced them, knew the cancer status of patients who provided the 34 urine samples.
The handler interspersed some urine samples that had a known cancer status so he could reward the dog for correct answers: alerting to a cancer sample by lying down, and turning away from a benign sample to alert the absence of cancer.
The dog's alert matched the final surgical pathology diagnosis in 30 of the 34 study samples. The sensitivity, or true-positive rate, was 86.7%, meaning Frankie correctly identified nearly 87% of the pathology-proven thyroid cancers. The specificity, or rate of true negatives, was 89.5%, which meant Frankie knew that a benign sample was actually benign almost 9 of every 10 times. There were two false-negative results and two false-positives using canine scent detection.
Bodenner said they plan to expand their program by collaborating with Auburn University College of Veterinary Medicine in Auburn, Alabama. The veterinary school reportedly will dedicate two of its bomb-sniffing dogs to become trained thyroid cancer-sniffing dogs using UAMS patient samples.