Early bowel cancer detected by dogs in Japan
By James Gallagher Health reporter, BBC news
A Labrador retriever has sniffed out bowel cancer in breath and stool samples during a study in Japan.
The research, in the journal Gut, showed the dog was able to identify early stages of the disease.
It has already been suggested that dogs can use their noses to detect skin, bladder, lung, ovarian and breast cancers.
Cancer Research UK said it would be extremely difficult to use dogs for routine cancer testing.
The biology of a tumour is thought to include a distinct smell and a series of studies have used dogs to try to detect it.
The researchers at Kyushu University used Marine, an eight-year-old black Labrador.
She was asked to pick from five samples, one of which was from a cancer patient and four from healthy people.
In the breath tests she picked out the cancer sample 33 out of 36 times.
She was even more successful with the stool samples, finding 37 out of 38 cancers.
Even early bowel cancers were detected, which is notoriously difficult.
The NHS screening programme tests for small amounts of blood in faeces, but the researchers believe it picks up only one in 10 early cases.
One in 20 people in the UK develop bowel cancer during their lifetime and more than 16,000 die each year.
Dr Hideto Sonoda, from Kyushu University, said: "It may be difficult to introduce canine scent judgement into clinical practice owing to the expense and time required for the dog trainer and dog education.
"Scent ability and concentration vary between dogs and also within the same dog on different days.
Some early research on developing an "electronic dog's nose" has taken place, which shows the potential for a cancer breath test.
Dr Sonoda told the BBC: "The specific cancer scent indeed exists, but the chemical compounds are not clear. Only the dog knows the true answer."
"It is therefore necessary to identify the cancer specific volatile organic compounds [smells] detected by dogs and to develop an early cancer detection sensor that can be substituted for canine scent judgement.
"To complete the sensor useful in clinical practice as a new diagnostic method is still expected to take some time."
Nell Barrie, science information officer at Cancer Research UK, said: "Although some dogs seem to be able to smell cancer in certain situations, we're still a long way from understanding exactly what they are detecting and this small study in one dog doesn't give us any new clues.
"It would be extremely difficult to use dogs as part of routine testing for cancer, and that's why further research in this area is concentrating on finding out more about the molecules given out by tumours, to see if they could be detected in other ways."
Mark Flannagan, chief executive of Beating Bowel Cancer, said: "This study looks interesting but it is for the scientists to verify whether these findings could lead to future developments for screening.
"The clear message is that screening saves lives and we encourage everyone eligible to take part in the existing NHS bowel cancer screening programme."
Colorectal cancer screening with odour material by canine scent detection
1. Hideto Sonoda1,6,
2. Shunji Kohnoe1,6,
3. Tetsuro Yamazato2,
4. Yuji Satoh3,
5. Gouki Morizono4,
6. Kentaro Shikata5,
7. Makoto Morita6,
8. Akihiro Watanabe6,
9. Masaru Morita1,
10. Yoshihiro Kakeji1,
11. Fumio Inoue4,
12. Yoshihiko Maehara1
+ Author Affiliations
1. 1Department of Surgery and Science, Kyushu University at Fukuoka, Fukuoka, Japan
2. 2Department of Internal Medicine, Arita Kyoritsu Hospital at Arita, Saga, Japan
3. 3St. Sugar Cancer Sniffing Dog Training Center at Minamibousou, Chiba, Japan
4. 4Department of General Surgery, Arita Kyoritsu Hospital at Arita, Saga, Japan
5. 5Department of Internal Medicine, Fukuoka Dental College Hospital at Fukuoka, Fukuoka, Japan
6. 6Department of General Surgery, Fukuoka Dental College Hospital at Fukuoka, Fukuoka, Japan
1. Correspondence to Dr Hideto Sonoda, Department of Surgery and Science Graduate School of Medicine Kyushu University 3-1-1 Midashi,Higashi-ku, Fukuoka 812-8582, Japan; email@example.com
* Revised 23 November 2010
* Accepted 7 December 2010
* Published Online First 31 January 2011
Objective Early detection and early treatment are of vital importance to the successful treatment of various cancers. The development of a novel screening method that is as economical and non-invasive as the faecal occult blood test (FOBT) for early detection of colorectal cancer (CRC) is needed. A study was undertaken using canine scent detection to determine whether odour material can become an effective tool in CRC screening.
Design Exhaled breath and watery stool samples were obtained from patients with CRC and from healthy controls prior to colonoscopy. Each test group consisted of one sample from a patient with CRC and four control samples from volunteers without cancer. These five samples were randomly and separately placed into five boxes. A Labrador retriever specially trained in scent detection of cancer and a handler cooperated in the tests. The dog first smelled a standard breath sample from a patient with CRC, then smelled each sample station and sat down in front of the station in which a cancer scent was detected.
Results 33 and 37 groups of breath and watery stool samples, respectively, were tested. Among patients with CRC and controls, the sensitivity of canine scent detection of breath samples compared with conventional diagnosis by colonoscopy was 0.91 and the specificity was 0.99. The sensitivity of canine scent detection of stool samples was 0.97 and the specificity was 0.99. The accuracy of canine scent detection was high even for early cancer. Canine scent detection was not confounded by current smoking, benign colorectal disease or inflammatory disease.
Conclusions This study shows that a specific cancer scent does indeed exist and that cancer-specific chemical compounds may be circulating throughout the body. These odour materials may become effective tools in CRC screening. In the future, studies designed to identify cancer-specific volatile organic compounds will be important for the development of new methods for early detection of CRC.
* canine scent detection
* colorectal cancer
* breath sample
* stool sample
* breath tests
* stool markers
* Funding This study was funded by Fukuoka Dental College.
* Competing interests None.
* Ethics approval This study was conducted with the approval of the institutional review boards at Fukuoka Dental College and Arita Kyoritsu Hospital and all subjects provided written informed consent.
* Provenance and peer review Not commissioned; externally peer reviewed.
This is an open-access article distributed under the terms of the Creative Commons Attribution Non-commercial License, which permits use, distribution, and reproduction in any medium, provided the original work is properly cited, the use is non commercial and is otherwise in compliance with the license. See: http://creativecommons.org/licenses/by-nc/2.0/ and http://creativecommons.org/licenses/by-nc/2.0/legalcode.
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