Which is better at detecting cancer, a laboratory or a Labrador retriever?


Dogs, which have 220 million olfactory cells in their noses compared with 50 million for humans, have long helped to sniff out survivors in search-and-rescue efforts. Now, a growing body of evidence supports the possible use of canines by clinicians, Bloomberg reports.


The largest study ever done on cancer-sniffing dogs found that they can detect prostate cancer with 98 percent accuracy by smelling urine samples. At least one application is in the works, seeking U.S. approval of a kit using breath samples to find breast cancer.


"Our study demonstrates the use of dogs might represent in the future a real clinical opportunity if used together with common diagnostic tools," said Gian Luigi Taverna, the author of the prostate cancer research.


When dogs sniff for cancer, they are detecting the chemicals emitted by a tumor. These chemicals are referred to as volatile organic compounds, or VOCs. VOCs have been found in the breath of lung cancer patients and colon cancer patients, as well as in the urine of prostate cancer patients. The most recent findings have spurred increased interest in dog cancer-detection research, including efforts to develop devices that can mimic the animal's exquisite olfactory system.


Consider the talents of Tsunami, a regal-looking dog with attentive eyes and an enthusiastic tail wag for her trainer friends. University of Pennsylvania researchers say she is more than 90 percent successful in identifying the scent of ovarian cancer in tissue samples, opening a new window on a disease that kills 14,000 Americans a year but lacks an effective test for early detection. When found early, the disease has a five-year survival rate of over 90 percent.