Cancer-sniffing dogs have potential for early-stage detection

As we enter the Year of the Dog, it seems an appropriate time to remember how invaluable our canine friends can be for us human beings. Guide dogs, assistance dogs, police dogs, rescue dogs -- they all are very helpful indeed. However, in addition to these kinds of canines, it is also worth mentioning cancer-sniffing dogs, who can play a key role in helping detect the ailment.

Currently, researchers are looking into the extent to which dogs can sniff out illnesses such as cancer in human beings, making use of dogs' refined sense of smell.

Esper is a 9-year-old female black Labrador retriever. She is also a cancer-sniffing dog. Upon being given the instruction "Search!" she begins to sniff a wooden box that contains a small bottle of human urine. If she senses that the urine "smells of cancer," she will sit down next to the box and make it known. If she doesn't, she will walk on by. Esper is one of five female dogs being trained by the company St. Sugar Japan based in Tateyama, Chiba Prefecture to detect cancer based on smell.

According to the dogs' trainer, Yuji Sato, 70, sniffing might appear to be a simple task but in fact, excellent concentration is required to reach accurate judgment. Therefore, just before the animals are asked to sniff away, they are given a ball to play with in order to raise their spirits.

So, to what extent can cancer-sniffing dogs such as Esper detect cancer based on smell? According to professor Masao Miyashita of Nippon Medical School Chiba Hokusoh Hospital, who is conducting joint research with St. Sugar Japan into cancer-sniffing dogs, the canines in a study correctly selected the urine of a cancer patient, out of five samples, on 333 out of 334 occasions (99.7 percent accuracy).

"Cancer has a 'common smell' (that the dogs can pick up on), and the dogs can pick up the smell regardless of where in the body the cancer is located. There's a chance that the dogs also have the potential to detect early-stage cancer," Miyashita says.

There are even some local governments that have been using these kinds of "diagnosis dogs" to assist with medical checkups. For example, in Kaneyama, Yamagata Prefecture, medical tests using cancer-sniffing dogs have been taking place on a trial basis, starting in fiscal 2017.

As of December 2017, "positive reactions" were found by the dogs in 11 out of 927 consenting people aged 40 or older who requested an appraisal of their urine. However, as Akiei Shibata, who is an official of a town-funded clinic working on this program, explains, "Additional tests are required to confirm whether the suspected cancer cases are in fact definitive," and is using testing such as CT scans as part of the final analysis.

There are some other issues, too. It is not entirely clear what substance the dogs are reacting to when they judge a urine sample to be linked to cancer, and there are questions over how to maintain their motivation. At times, the dogs start to feel less motivated when they continue to come across urine that does not have "the smell of cancer." Therefore, it becomes necessary to take measures such as providing the urine samples of cancer patients in order to maintain the dogs' motivation and concentration.