Animals Being Used to Diagnose Cancer

It’s usually complicated and incredibly expensive to develop a new way to screen for cancer or to diagnose other serious medical problems — but not always! I just learned about a promising new approach to detecting cancer that requires no radiation, no blood sample and no biopsy… is cost effective and highly accurate… and furry. Researchers are finding that dogs and other animals can be highly effective at finding the disease in humans early, accurately and economically. Moreover, when animals detect a disease, the procedure is noninvasive.

Several years ago I reported on dogs “smelling” skin cancer. Since then, the field has expanded in very exciting ways. To find out more about this research, I contacted two leading scientists in the field. In speaking with them, I got an inside look at research that will almost certainly have a major impact on health care.

The Breath Test

Michael McCulloch, LAc, MPH, PhD, is the head researcher of the Pine Street Foundation, a cancer research organization in San Anselmo, California. Dr. McCulloch told me that in one of the foundation’s recent studies, a group of 86 volunteer patients known to have breast or lung cancer at varying stages were asked to breathe into small containers that stored their exhaled breath. Later, two groups of volunteers sniffed some of each patient’s exhaled air. The first group of volunteers was human, while the next group consisted of three Labrador retrievers and two Portuguese water dogs, all trained to sit or lie down when they smelled the exhaled breath of a person with cancer. Their results were compared with results on exhaled breath samples from 83 healthy people.

While dogs are not yet being used to diagnose cancer, the results of the study were more than promising. The human sniffers failed to pick up on any of the cancer patients. But for the dogs, Dr. McCulloch said that “the accuracy in lung cancer was 99% and in breast cancer it was 88%” — adding that the accuracy rate was higher than it is with standard diagnostic methods. He said that more research is necessary before the canine crew can be put to work. In particular, there needs to be a comparative study where the breath sniffing is included during routine cancer screening, with the outcome evaluated against accepted diagnostic protocols — and examined after a period of time. A study like this would extend over, say, five years, when cancer might be either confirmed or excluded, as this would help to see whether dogs are able to detect the disease even before symptoms develop.

By the way, the dogs used in the research at Pine Street aren’t some lab-bred super-pooches — they are family pets. It takes two to three weeks to train them, and they work three to five days a week. After work, they go home. “We’ve learned that a happy dog is a more accurate sniffer,” Dr. McCulloch said.

Bruce Kimball, PhD, is a chemist with the National Wildlife Research Center and works with the Monell Chemical Senses Center in Philadelphia. Monell, a nonprofit research institute, is one of several organizations looking into new ways of using animals to detect disease.

At present, Dr. Kimball is working at training mice to identify the feces of ducks infected with avian influenza, a disease that can cause illness and death in humans as well as birds. And, he told me, mice have been taught to successfully distinguish between animals that have been vaccinated for rabies and those that haven’t.

Though some people may find all of this surprising, the truth is that animals’ detection abilities are familiar in other spheres of life — police bloodhounds… drug- and explosive-sniffing dogs at airports and border crossings… rescue dogs searching for signs of life in the rubble after natural disasters… “service” dogs who are able to detect imminent seizures. Dr. Kimball said that on several occasions, dogs have located land mines that were overlooked by mechanical sensors — on the other hand, he’s never heard of a machine that found a mine that a dog had missed. And not long ago, The New England Journal of Medicine reported that a cat in a nursing home identified residents who were near death by making frequent visits to those patients’ rooms. The operative theory is that the cat could smell the chemical changes associated with a person’s end-of-life transition, a process called cellular necrosis, where the body’s cells begin to degrade.

From Labradors to Laboratories

Researchers are working at a fast pace and headed in several directions.

For instance, dogs are being trained to detect a wider range of diseases. Pine Street Foundation is preparing to study patients with ovarian cancer — their breath will undergo both dog-sniffing tests and chemical analysis. Prostate cancer, skin cancer and tuberculosis are on the target list of researchers as well. “Any disease that changes the odor signature of the body will lend itself to this method,” Dr. McCulloch said.

Meanwhile, several organizations are working to develop technology or laboratory analysis techniques that mimic the sensory systems of animals in detecting diseases. The University of Maine, for example, is teaming up with the Pine Street Foundation to devise a lab tool that analyzes the breath of people suspected to have cancer to determine whether more testing should be done or whether they should remain under close observation. And researchers at Monell have been at work on a mechanical nose that provides this information.

While science rarely succeeds in duplicating nature, it is not yet known which — a device or the real live animal — will be better at detecting disease. So in the meantime, think of it as a nose-to-nose competition!

Information on volunteering and to participate in the Pine Street Foundation study is available at http://PineStreetFoundation.org.