Sensing Cancer With Dogs

Dogs can smell cancer on patients' breath, according to studies.

Dogs have an uncanny ability to smell cancer on afflicted people's breath, according to researchers at the Pine Street Foundation, a cancer research organization in San Anselmo, California. As of 2010, dogs have successfully identified skin, bladder, lung and breast cancer by scent alone. Further study is needed, but foundations like Pine Street believe dogs could prove instrumental in the detection and treatment process of cancer patients.

Pine Street Foundation Study

In 2006, the Pine Street Foundation began to publish the results of its study confirming minimally trained dogs could detect lung and breast cancer with high levels of accuracy merely by smelling a patient's breath, even in very early stages of the disease. A handful of labrador retrievers and Portuguese water dogs participated in a few weeks of basic training using food reward techniques. At the conclusion of training, the dogs were able to accurately identify 99 percent of lung cancer patients and 88 percent of breast cancer patients via a double-blind study using breath samples captured in test tubes.

In 2004, the Florida State University Sensory Research Institute in Tallahassee conducted similar studies confirming dogs could smell melanomas, or skin cancers.

Chemicals in Cancer

Cancer cells produce metabolic wastes that differ from those of normal cells, according to Nicholas Broffman, executive director of the Pine Street Foundation. Chemicals such as alkanes and benzene derivatives are emitted in the breath of cancer patients, which the dogs can sense in parts per trillion.

Canine Sense of Smell

A dog's sense of smell is 10,000 to 100,000 times better than humans, according to James Walker, the director of the Sensory Research Institute at Florida State University in Tallahassee. No one is sure exactly why this is so, but what is known is that more of the canine brain is dedicated to smell than is the human brain. There is also a greater convergence of neurons from the nose to the brain, Walker said. In the Pine Street study, results proved it didn't matter what dog smelled which sample, or at what stage the cancer was; the same level of accuracy was achieved.

Dog Noses versus Technology

"The dog's brain and nose hardware is currently the most sophisticated odor detection device on the planet," said Michael McCulloch, the leader of the Pine Street study.

While scientists agree that diagnoses must be confirmed with traditional tests, no piece of technology or equipment, as of 2010, can match the dog's ability to sense cancer so accurately in such a non-invasive and quick way.

Application

McCulloch and others hope to see dogs trained to smell out cancers, like those in the Pine Street study, in medical settings around the world. Because early detection greatly increases survival rates, and because canines can sense cancer quickly even in its early stages with no harm to the patient, research leaders like McCulloch believe these animals could prove instrumental in detecting, treating and saving cancer patients' lives. Dogs, however, are not currently widely used for this purpose as of 2010.

References

• National Geographic: Dogs Smell Cancer in Patients' Breath, Study Shows
• New Scientist: Health: Dogs as Good as Screening for Cancer Detection