January 2006 - Dogs have long been used to sniff out explosives, narcotics, and even counterfeit currency.
Now, a new study shows that man's best friend can also detect lung and breast cancer in breath samples.
"When we heard anecdotally that there was a device out there that might be able to detect cancer at its earliest stages, before it even shows up on an MRI [magnetic resonance imaging], it was something we wanted to pursue," said Nicholas Broffman, executive director of the Pine Street Foundation, a nonprofit group in California that conducted the study. The group helps cancer patients who are facing tough treatment decisions.
That device, of course, is a
dog, and researchers believe it picks up on chemical differences that
linger in the breath of a person with cancer.
While canines won't ever replace standard medical testing, experts think they may become an important early screening tool in the future.
In this study, three Labrador retrievers and two Portuguese water dogs were trained in three weeks to either sit or lay down in front of breath samples from lung and breast cancer patients, while ignoring those of healthy individuals.
"These were not super dogs," said Broffman. "They were just ordinary household pets."
The trial comprised of breath samples from 55 patients with lung cancer, 31 with breast cancer, and 83 healthy people. The samples were captured in special tubes.
All cancer patients had recently been diagnosed through conventional methods, such as mammograms or CT scans, but had not yet begun chemotherapy. And the trial samples were different from the ones used to train the dogs.
The results show the dogs were 88 percent to 97 percent accurate in identifying both early- and late-stage breast and lung cancers.
The study will appear in the March issue of Integrative Cancer Therapies.
Catching cancer early increases survival rates and allows for treatment with lower toxicity, experts say.
The ability of dogs to detect cancer was first discovered in 1989, and reported in the medical journal The Lancet. A woman's pet had alerted her to the presence of melanoma by constantly sniffing the skin lesion on her leg. Subsequent studies have shown dogs can smell melanoma and bladder cancer.
"I think all of these [studies and observations] are saying this ought to be looked at more carefully and ought to be taken seriously," said James Walker, director of Florida State University's Sensory Research Institute in Tallahassee.
He says a dog's nose is so powerful it can detect odors 10,000 to 100,000 times better than a human nose can.
Later this year, he plans to launch a study on canine detection of bladder cancer.
Veterinarian Larry Myers, from Auburn University in Alabama, is currently working on four canine-cancer detection projects.
He said he has some doubts, though, about the Pine Street study.
"What makes me a little curious about this is they are talking about three weeks of training for these dogs and getting [a high] percent of accuracy," Myers said.
In the past, Myers has trained dogs to find everything from drugs to off-flavored catfish, but it usually takes him five to six weeks. The U.S. military, he pointed out, spends about three months training explosive detection dogs.
Regardless of training differences, Myers thinks dogs could be used five to 10 years from now to screen for cancer at local health fairs or in Third World countries.
In the meantime, though, more research has to be done.
"Everybody needs to be careful and not overstate how wonderful these [studies] are," said Myers. "We need to approach [this type of research] slowly, cautiously and scientifically."
More information
For more on dogs and their cancer-detecting abilities, go to Sensory Research Institute.
SOURCES: Nicholas Broffman, executive director, Pine Street
Foundation, San Anselmo, Calif.; James Walker, Ph.D., director, Sensory
Research Institute, Florida State University, Tallahassee; Larry Myers,
associate professor, Auburn University College of Veterinary Medicine,
Auburn, Ala.; March 2006 Integrative Cancer Therapies
This is a story from
WomensHealth.gov -
U.S. Department of Health & Human Services, Office on Women's Health