برای دیزی این سگ یازده ساله، روز کاری ممکن است شبیه بازی باشد. اما این بازی می تواند جان افراد را نجات دهد چون او قادر است نشانه های اولیه بروز سرطان پروستات را تشخیص دهد. For 11-year-old labrador Daisy, a day's work is one big game. But that game could saves lives by helping to spot the early signs of prostate cancer. Daisy is one of a batch of dogs approved for trial by Britain's National Health Service for their ability to sniff out the odours associated with the disease. Dr Claire Guest founded the charity Medical Detections Dogs to train specialist dogs to detect human diseases. She says dogs have three-hundred million sensory receptors in their nose, compared to just five million in humans. (SOUNDBITE) (English) DR. CLAIRE GUEST, CHIEF EXECUTIVE AND DIRECTOR OF OPERATIONS OF MEDICAL DETECTION DOGS, SAYING: "What we now know is that cancer cells that are dividing differently have different volatile organic compounds -- smelly compounds -- that are associated with the cells. And dogs with their incredible sense of small can find these in things like breath and urine." During training, dogs do the rounds... sniffing a machine that holds eight urine samples. When they sniff the sample that contains cancer cells, they either stop and sit down by it, bark, or lick the bottle to indicate they can smell the cancer. (SOUNDBITE) (English) DR. CLAIRE GUEST, CHIEF EXECUTIVE AND DIRECTOR OF OPERATIONS OF MEDICAL DETECTION DOGS, SAYING: "These dogs have the ability to screen hundreds of samples in a day; it's something they find very easy, they enjoy their work. To them it's a hunt game - they find the cancer." Initial trials showed trained dogs can detect prostate tumours in urine in 93 percent of cases. Researchers hope they could provide a second line cancer screening service, to be used alongside the prostate specific antigen test, which has a high 'false positive' rate. And it's not just prostate cancer that dogs can sense. (SOUNDBITE) (English) ROWENA FLETCHER, HEAD OF RESEARCH AND DEVELOPMENT AT MILTON KEYNES UNIVERSITY HOSPITAL, SAYING: "So a lot of different diseases could carry a chemical signature, and then really the dogs could be used potentially to look at any other diseases which also had a chemical signature." Ultimately, scientists want to recreate the dog's remarkable sense of smell in an 'electronic nose'. SOUNDBITE) (English) ROWENA FLETCHER, HEAD OF RESEARCH AND DEVELOPMENT AT MILTON KEYNES UNIVERSITY HOSPITAL, SAYING: "So eventually you could have a machine that sits on your consultant's desk, you'd put the urine sample in it and it would tell you if it was positive or negative." This is still some way off, with no current technology able to get close to the sensitivity of the dog's nose. So until science catches up, man's best friend could be his greatest ally in the fight against prostate cancer.