MYAKKA CITY, Fla - Dogs with a strong sense of smell, such as beagles, could help in early detection of certain lung cancers in humans, a recent study suggests.
The study, published in the Journal of the American Osteopathic Association, used a small sample size of dogs to differentiate between healthy blood serum samples and those of people with lung cancer.
Researchers said they chose to focus on lung cancer detection because it is the leading cause of cancer deaths worldwide for men and women, according to the American Cancer Society.
The nonprofit also reported that 13 percent of new cancers are a form of lung cancer and more than 200,000 people are diagnosed in the U.S. each year.
Researchers said early detection provides the best way for people to survive cancer but because symptoms for lung cancer typically don't appear until the later stages, early detection can be difficult. In addition, certain detection methods such as chest X-rays can be costly and add to health problems.
The study was also done to help researchers continue their search for more cost-effective and less invasive ways to spot lung cancer early.
Since the 1980s, variations of electronic nose technology have been used to look for certain smell patterns of chronic diseases. In one study, an e-nose found biomarkers for lung cancer. But, the current study indicated that effectiveness using e-nose tech varied widely and could not compete with how well dogs can smell.
"The olfactory acuity of a dog is at least 10,000 times more sensitive than that of a human, which is likely due to their more expansive olfactory epithelium and olfactory receptors and their ability to retain air in their nasopharynx during exhalation," the study said.
Since certain dog breeds have stronger senses of smell than others, researchers chose beagles to be part of the detection study.
Over the course of eight weeks in 2017, researchers trained three beagles to detect samples with non-small cell lung cancer. The training and testing phases took place in Myakka City, Florida, according to the study's abstract.
During the training phase, samples were provided by Boston BioSource. The samples contained blood serum from people who were newly diagnosed with lung cancer and had not started any treatments. The control samples were donated by healthy men and women through the same company.
Researchers said they chose non-small cell lung cancer as the cancer for the dogs to detect because it's more common and easier to treat when detected early.
In order to train the dogs, samples were placed in syringes and into metal canisters that had multiple holes. The canisters with cancer and control samples were evenly placed at the dogs' eye level.
Each session, the dogs were followed by a handler as the dog sniffed five canisters, four of which contained a control sample and one that had the cancer sample. Dogs were given as much time as they needed to smell each canister.
Each dog was asked to indicate the correct sample by sitting in front of the canister. If the dog sat in front of a control sample, they were told "no" and asked to move to the next canister. If the dog correctly identified the cancer sample, they were given a treat and heard the sound of a clicker.
The training was done in three phases over the eight-week period. In the final training phase, the dogs were weaned from the treats until they could positively ID a sample without one.
When the testing phase began, a double-blind procedure was used, according to the abstract.
Ten new samples from lung cancer patients were used during the testing phase, which was done in one day.
Each dog did 10 test runs and each session was set up like a training phase. But this time, the dogs were only given 5 to 10 seconds to sniff each sample and then had to ID the correct blood sample. A 10-minute resting period was done between each run so that the smell of previous samples could dissipate and the scent of new samples filled the room.
The first canine identified 10 out of 10 cancer samples and only incorrectly identified one out of 40 control samples. The second canine identified 10 out of 10 samples correctly as well and did not incorrectly ID any control samples.
The final dog identified nine out of 10 cancer samples correctly, but incorrectly identified two of the 40 control samples as cancerous.
In the end, the dogs had around a 97 percent accuracy rate and researchers said the study supports the use of scent hounds to help detect cancer in people.
Still, researchers indicated more studies with larger sample sizes need to be done to further support the data.