Japanese scientists have found that dogs can distinguish people with colorectal cancer, reporting that a retriever can scent bowel cancer in breath and stool samples as accurately as hi-tech diagnostic tools.The researchers have been relying especially on Marnie, a specially trained black labrador retriever with a lot of talent for the job. Over a period of several months, Marnie was given 74 sniff tests to carry out. The tests were each comprised of stool and breath samples, one of which was cancerous. Every time she correctly identified a cancerous sample, she was rewarded with some time with her tennis ball:
The findings published in the British Medical Journal support hopes for an ‘electronic nose’ that will one day be able to sniff out the specific chemicals that are produced by cancer cells and circulate in the blood stream before being expelled by the lungs.
The samples came from 48 people with confirmed bowel cancer at various stages of the disease and 258 volunteers with no bowel cancer or who had had cancer in the past. They complicated the task for the eight-year-old canine detective by adding a few challenges to the samples.According to Cosmos, for eight-year-old Marnie, cancer sniffing is a second career. She was first trained for water rescue. (Who says you can’t teach an old dog new tricks?)
Around half of the non-cancer samples came from people with bowel polyps, which are benign but are also a possible precursor of bowel cancer. Six percent of the breath samples, and 10% of the stool samples, came from people with other gut problems, such as inflammatory bowel disease, ulcers, diverticulitis, and appendicitis.
The retriever performed as well as a colonoscopy, a technique in which a fibre-optic tube with a camera on the end is inserted into the rectum to look for suspect areas of the intestine. It correctly spotted which samples were cancerous and which were not in 33 out of 36 breath tests, equal to 95% accuracy, and in 37 out of 38 stool tests (98% accuracy).