Sniffing Out Cancer
Medical researchers have been unable to find a screening test for ovarian cancer. Could dogs be the answer?
Three years ago in a lab at the University of Arkansas for Medical Sciences in Little Rock, Donna Waugh introduced her border collie, John D., to ovarian-cancer tissue.
Waugh and her research partner, gynecologic oncologist Dr. Alexander “Sandy” Burnett, weren’t sure there would be any scent for the dog to find. But if any dog could find it, John D. could.
A few hours later, the trained search-and-rescue dog was able to detect the difference between cancerous and noncancerous tissue samples. The dog had locked onto a scent. That scent could be a solution.
Ovarian cancer is a silent killer. With no defined screening test and unreliable symptoms, a diagnosis doesn’t usually come until advanced stages of the disease. But Waugh and Burnett believe that the use of search-and-rescue dogs could be one of the most promising tests for ovarian cancer yet.
The experiment is not the first to use dogs’ ultra-sensitive sense of smell to detect cancer.
“In the ’90s, there were a few case reports of folks whose dogs would not leave them alone, … and [the people] were ultimately diagnosed with cancer,” Burnett says. “Since then, dogs have been shown to be able to detect melanoma on the skin, and there have been studies to detect a scent associated with colon cancer, breast cancer [and] lung cancer.”
In 2010, studies using dogs had become so buzzed about that Dr. Ted Gansler, director of medical content for the American Cancer Society, wrote that the studies aren’t as strange as they may initially sound.
“Scientists have already identified some of the chemical differences between normal and malignant tissues, so it is not surprising that some dogs can also recognize these differences,” Gansler wrote for Cancer.org.
Waugh and Burnett were familiar with other studies using search dogs to detect cancer, and they decided to see if it would work in this case as well.
Waugh first met Burnett in 2010, when he treated her for a benign ovarian tumor. As the two talked during appointments, they bonded over being dog people.
“It was sort of a serendipitous meeting,” Burnett says. “She said she ran Arkansas Search and Rescue and talked about how good the dogs were at picking up a scent. It [eventually] came to the idea of, ‘Wouldn’t it be great if we could pick up a scent associated with ovarian cancer?’”
After Waugh’s dog, John D., was able to recognize the cancer’s scent so quickly, Waugh and Burnett brought in more search-and-rescue dogs and volunteers. Each of the 10 dogs trained over the past two years has been a rescue dog—all working breeds, including German shepherds, Labs and golden retrievers.
“We exposed the dogs to fresh ovarian-cancer tissue and gave a specific command,” Burnett says. “The dogs would light on that scent and wouldn’t react to the benign ovaries.”
The command is a totally original, nonsensical word to keep the dogs from starting to search if someone casually says the word in public.
Once the dogs were able to pick up the cancer scent through the tissue, Burnett decided to see if the scent would also be detectable in urine. Using samples from women with ovarian cancer and with benign tumors, dogs were introduced to several samples at once. Each time, they identified the cancerous tissue, leaving the benign samples alone.
“It was by far the most interesting thing, because that could be a potential screening test,” Burnett says. “What could be less expensive than taking a urine sample and seeing if the dogs could sniff out the cancer?”
The test could also be easily replicated in any town around the world that has trained search-and-rescue dogs. For the dogs, learning the scent of ovarian-cancer tissue would be no different than a human learning to recognize the smell of popcorn or coffee.
“Once they know it, they know it for life,” Waugh says.
Now, Waugh, Burnett and the volunteers are working every other weekend, doing blind trials in which the dogs attempt to determine whether a urine sample is positive or negative. Once the researchers have an idea of how consistently the dogs are accurate, Burnett says, they will move forward with a screening trial involving samples from hundreds of women. Burnett hopes they will be able to move to this step by the end of the year.
“If that were successful, then you look at an honest-to-goodness population screening trial with hundreds of thousands of women,” Burnett says. “We’d need quite a bit of funding.”
So far, the study has been done on the hospital’s own dime, with volunteers donating their time, and specimens collected from Burnett’s patients. A population screening trial could cost upward of $500,000, Burnett says.
But do Waugh and Burnett picture a future with a dog in every OB/GYN office?
“I don’t think anybody really believes you’ll have a dog in a doctor’s office,” Waugh says. “But we hope if we can isolate what the dogs are detecting, we can start looking for that.”
Burnett says that if the odor can be isolated, technology could replace the dogs with a machine, as has been done for bomb-sniffing and drug-sniffing.
“The machines have gotten good, but so far they’re not comparable to what the animal can do,” Burnett says.
Burnett says he was surprised by how quickly the dogs were able to detect the ovarian-cancer scent, but Waugh wasn’t.
“After we talked, Dr. Burnett called me back and said, ‘Do you really think a dog can do this?” Waugh says. “We had just gone to a search in Pine Bluff for a drowning, and John D. was able to locate a body in deep water with a fast current. … If he can do that, I told Dr. Burnett, he can do anything.”