A 4-year-old Labrador and a 7-year-old Vizsla were trained to detect the odor of prostate cancer in urine samples collected from patients with the disease, including Gleason 9 prostate cancer -- the most lethal tumors that would benefit the most from early detection. Results showed the dogs correctly identified positive samples 71% of the time, and correctly ignored negative samples including those with other diseases 70% to 76% of the time. The dogs also correctly identified when 73% of blinded patient samples did not have the disease, which compares favorably to the most commonly used prostate cancer test, the PSA blood test. "This study showed that a dog's nose could hold the key to an urgently needed, more accurate, and non-invasive method of early prostate cancer diagnosis," said Claire Guest of Medical Detection Dogs, lead author of the study. "…. This has enormous potential and in time the ability of the dogs' nose could be translated to an electronic device."