“The first medical journal to report on cancer-sniffing dog was The Lancet, which in 1989 published a case study showing that a dog sniffed a cancerous tumor which doctor had not yet found out,” says Doctor Miyashita, a surgeon and a medical researcher at the Nippon Medical School Chiba Hokusoh Hospital. Dr. Miyashita has been working on the research to identify the mechanism of cancer detection by dogs.
According to the above case study, a woman attended a nearby medical clinic because of an elevated scar found on her leg. The doctor did not take it seriously and told the woman it was just a cosmetic matter and nothing to worry about. However, her dog had different thoughts. Because the dog kept on sniffing the scar repeatedly even after the visit to the clinic, the woman gave in and soon visited a dermatology specialist.

A diagnosis made by the dermatologist was a skin cancer, known as “malignant melanoma”. Fortunately, the cancer was still in its early stage and was cured by removing the part. “ This report concluded that some dogs might have a special ability to sniff elements coming from cancer. However, it also suggested that in order to confirm this theory, more clinical reviews are needed.”

In 2004, another research on cancer sniffing dog was reported in a famous medical journal, but this time it was not a case report but a research report based on a clinical trial. Clinical trials are a type of research methods known to have more solid scientific evidence than that of case reports. This research showed that cancer-sniffing dogs were able to successfully detect 144 urine samples derived from cancer patients and healthy individuals. The success rate was 41%, which was significantly higher than that of coincidence (14% in this study). This study showed for the first time that dogs could detect cancer with statistical significance.

However, according to Dr. Miyashita, a dog used for researches at the Nippon Medical School has a much higher detection rate of cancer when compared to the rate of above 2004 study. “The dog we use in our study is a 10-year-old female Labrador retriever called Marine. She is very well trained and has an astounding ability to detect cancers”, says Dr. Miyashita. “We recently found that Marine can detect cancers at a very high rate, almost with 100% success rate, in cancers such as cervical cancers, mammary cancers, ovary cancers, and stomach cancers”, says Dr. Miyashita.

For example, Marine detected all 47 urine samples derived from cervical cancer patients, while she did not choose any samples derived from healthy individuals as cancer samples. This shows that the Marine’s detection rate for cancer was both 100% in terms of sensitivity and specificity.

“We are continuing studies using Marine for detecting various cancers and at various stages. To date, we found out that Marine can detect cancers even at its very early stages. Our current goal is to detect what molecules Marine is sensing for the detection of cancers,” says Dr. Miyashita.