Colorectal cancer screening with odour material by canine scent detection

Department of Surgery and Science, Kyushu University, Fukuoka, Japan.
Gut (Impact Factor: 14.66). 05/2011; 60(6):814-9. DOI: 10.1136/gut.2010.218305
Source: PubMed


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.
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.
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.
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.

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Available from: Tetsuro Yamazato
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    • "Colorectal cancer Sonoda et al. (2011) "
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    ABSTRACT: Numerous studies have attempted to demonstrate the olfactory ability of canines to detect several common cancer types from human bodily fluids, breath and tissue. Canines have been reported to detect bladder cancer (sensitivity of 0.63-0.73 and specificity of 0.64-0.92) and prostate cancer (sensitivity of 0.91-0.99 and specificity of 0.91-0.97) from urine; breast cancer (sensitivity of 0.88 and specificity of 0.98) and lung cancer (sensitivity 0.56-0.99 and specificity of 8.30-0.99) on breath and colorectal cancer from stools (sensitivity of 0.91-0.97 and specificity of 0.97-0.99). The quoted figures of sensitivity and specificity across differing studies demonstrate that in many cases results are variable from study to study; this raises questions about the reproducibility of methodology and study design which we have identified herein. Furthermore in some studies the controls used have resulted in differentiation of samples which are of limited use for clinical diagnosis. These studies provide some evidence that cancer gives rise to different volatile organic compounds (VOCs) compared to healthy samples. Whilst canine detection may be unsuitable for clinical implementation they can, at least, provide inspiration for more traditional laboratory investigations.
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    • "Therefore, there is a clear demand for a more economical, noninvasive and efficient detection method. Sonoda et al. (2011) used one Labrador retriever that had previously been trained for water rescue, and was retrained as a cancer detection dog using a reward based approach (7). Using both breath and watery stool samples of colorectal cancer patients and healthy controls, they found 91% sensitivity and 99% specificity for breath samples, and 97% sensitivity and 99% specificity for watery stool samples. "
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    • "2 Giant Schnauzer Double blind Blood and tissue In the study the authors calculated a sensitivity of 100% and a specificity of 95% for tissue sample tests, and a sensitivity of 100% and a specificity of 98% for blood sample tests Greater number of samples Inclusion of other inflammatory processes besides cancer and other confounders (i.e., smoking) in the control group [20] Colorectal cancer 1 Labrador Retriever Double blind Breath and watery stool samples The authors calculated a sensitivity for canine scent detection of 91% and 97% for breath tests and watery stool tests, respectively; a specificity of 99% for, both, breathe tests and watery stool tests Greater number of samples Inclusion of more inflammatory processes and a greater number of confounders in the control group Inclusion of a greater number of dogs in the study [21] Prostate cancer 1 Belgian Malinois Shepherd Double blind Urine The calculated sensitivity and specificity was 91% Greater number of samples Inclusion of a greater number of dogs in the study [22] "
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