Dogs are not only loving companions. They could also be our most reliable weapon against cancer.

In a Japan first, a small, agrarian community in Yamagata Prefecture will start using specially trained dogs this month to screen its residents for cancer.

If the pilot project in the town of Kaneyama, which has a population of 6,000, takes off, it could dramatically change the way cancers are screened in this country.

The town said it will ask residents over age 40 who take part in municipal health checkups to voluntarily turn over urine samples. Once frozen, the samples will be sent to Nippon Medical School Hokusoh Hospital in Inzai, Chiba Prefecture, which is working with the St. Sugar Japan Cancer Sniffing Dog Training Cancer, a private company also in Chiba, to get specially trained dogs to sniff out samples containing cancerous cells.

But why Kaneyama?

Northern parts of Japan have long been known for higher-than-average cancer mortality rates, with experts attributing the trend to heavy drinking and high salt intake through foods such as tsukemono (pickles).

But town officials were appalled last year when they read a detailed report on cancer mortality rates published in a monthly magazine, said Akiei Shibata, an official of a town-funded clinic who is in charge of the project.

In the June 2016 issue of the Chuo Koron magazine, the Mogami district of Yamagata — which covers eight municipalities including Kaneyama — had the highest mortality rate for stomach cancer in women between 2008 and 2012, out of the nation’s 344 “secondary medical districts.”

Such districts are government-designated regional health care units that include a certain number of hospital beds. Several municipalities typically make up a single district.

A few months later, Kaneyama Mayor Hiroshi Suzuki met with Dr. Masao Miyashita, a surgeon and deputy president of the Nippon Medical School Hokusoh Hospital, who is also a canine cancer detection expert, when he was visiting the town for a lecture.

Suzuki asked Miyashita for advice on how to improve the town’s dismal health status, and the idea of using dogs to detect early stages of cancer came up, Shibata said.

“Dogs are known for their good sense of smell, but these specially trained dogs have an exceptional ability to sniff out smells of cancer, so superearly detection is possible,” Shibata said. “Currently, stomach cancer is screened with an X-ray or gastroendoscopy, but some people find these to be physically demanding. But if cancer can be detected with just a urine test, more people would feel like getting screened. We want to create a system where cancer can be discovered in the earliest stages.”

The town hopes to attract 1,000 volunteers per year and has set aside ¥11 million for the project during the current fiscal year.

Shibata added that the town will continue to carry out traditional cancer screenings and use canine sniffers as an additional tool.

Dogs at St. Sugar Japan, a pioneering dog training center, are trained to react to any type of cancer, Miyashita said, noting that people whose samples test positive will be asked to see a specialist.

Miyashita added that dogs can smell cancer with “almost 100 percent accuracy,” though it is not known exactly why they are so great at it. One promising theory, he said, is that dogs are capable of smelling a mixture of gases that are produced only by cancerous cells.

“Cancer cells are extremely active,” Miyashita said, noting that a series of biochemical reactions that take place inside cells, called a metabolic pathway, are different in cancerous cells and normal cells. “It has long been known that cancer cells convert glucose into energy, whereas normal cells convert oxygen. That might be linked to the apparent fact that cancerous cells emanate particular types of gases. Dogs are probably smelling such substances.”

Dogs can sniff out various types of samples, including breath, urine, saliva and feces.

In 2011, a team of Japanese researchers including those at St. Sugar Japan and Hideto Sonoda, an assistant professor at Kyushu University, caused a sensation when they published a paper on canine cancer detection in the British medical journal GUT. In the paper, they said a specially trained dog sniffed out biological samples from cancer patients with at least 90 percent accuracy.

In the experiment between November 2008 and June 2009, the researchers got an 8-year-old female Labrador retriever to sniff samples from about 300 people. In a test using five containers with breath samples, the dog correctly chose samples taken from a patient with colon cancer 33 out of 36 times, they said.

In another test using watery stool samples, she chose the correct samples 37 out of 38 times.

But using dogs is not common due to the high cost and time investments required for training. There are now only five cancer-sniffing dogs in Japan, all at St. Sugar Japan.

Kaneyama’s project, which will run for three years, can take the research further, Miyashita said, adding that the results will need to be closely examined.

“Our goal is to come up with a cancer detection method that would be more efficient, cost less and become a better tool to find curable cancers than conventional methods,” Miyashita said. “The Kaneyama project is a good start. But if we were to expand this further, we will need more dogs. Five are not enough to screen all people in Tokyo, for example.”

Shibata agrees, noting that the town thinks its investment is worth the money.

“Early detection will lead to early treatment, which will save medical expenditures in the end,” he said. “It’s true that at present, the screening cost is much higher than for conventional tests. The technique is still in the research stage. But we hope to help create momentum for canine cancer screening.”

A Matter of Health is a new weekly series on the latest health research, technology or policy issue in Japan. It appears on Thursdays.

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