Canine cancer detection

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Canine cancer detection is an approach to cancer screening that relies upon the claimed olfactory ability of dogs to detect, in urine or in breath, very low concentrations of the alkanes and aromatic compounds generated by malignant tumors.

While some research has been promising, no verified studies by secondary research groups have substantiated the validity of positive, conclusive results.

Background[edit]

It is claimed that dogs can detect some substances on the order of parts per trillion, and evolutionary hypotheses explaining the ability of dogs to detect human cancers have been proposed.[1][2]

Media coverage[edit]

The proposal that dogs can detect cancer attracted widespread coverage in the general media. In 2015 the Huffington Post reported that studies have suggested that dogs may be able to detect lung cancer, melanoma, breast cancer and bladder cancer, and that dogs can be trained to detect cancer in 93% of cases.[3] In 2016, actress Shannen Doherty told Entertainment Tonight in an interview that her dog identified her breast cancer before doctors could diagnose it.[4] National Geographic said that "man's best friend can detect various cancers, including prostate cancer, colorectal cancer and melanoma."[5]

On the other hand, a review by Australian Popular Science found that the more rigorous trials produced less positive results.[6] Another trial reported in Nature World News found disappointing results, but nevertheless "the researchers... believe that one day, dogs can still detect lung cancer."[7]

NBC reported that Britain’s National Health Service is behind the first clinical trial to test the ability of canines to detect cancer.[8]

Research[edit]

Although the first suggestion of this approach in a medical journal, The Lancet, dates back to 1989,[9] there were only occasional publications on the subject in the next decade.[10]

However, two studies (one published in 2004[11][12][13] and one in 2006), involving detection in urine, had promising results, with the 2006 report claiming a 99% accuracy in detecting lung cancer,[14] although both studies were preliminary and involved small numbers of patients.

In a 2011 study, lung cancer was identified with a sensitivity of 71% and a specificity of 93%, using breath samples.[15] Other studies, also with breath samples, have found promising results.[16]

Application[edit]

There are two proposed benefits, assuming that further studies corroborate the initial results.

  • Some researchers believe that dogs will become integrated directly into patient care, akin to their use in detecting bombs and drugs, as well as locating missing people.
  • Others recommend that the skill of dogs in detecting cancer would be more appropriately confined to labs, where gas chromatographs could be used to isolate which specific compounds the dogs identified. Recent developments include a simple breathalyser which changes colour according to the compounds in the breath, indicating the presence of cancer.[17]

Skeptical analysis[edit]

In a May 25, 2012 article, “What to make of Medical Dogs” published by Science-Based Medicine, Peter Lipson reported on his review of the scientific literature regarding these claims and found valid support for positive conclusions to be lacking:

While anecdotes abound, there is scant literature to support this ability. One unimpressive pilot study looked at dogs’ potential ability to detect bladder cancers from urine samples. The idea behind cancer dogs is that there may be volatile compounds produced in cancer patients that dogs can detect by scent. In these studies, the compounds are not identified, not tested for, not named. There are many confounders, for example, in the few samples used, there may be other differences being detected by the dogs.[18]

In the other study (I found very few) dogs were “trained” to detect lung and breast cancers in humans. The methodology of breath sampling is not validated as far as I can see, and once again, the putative compounds in breath are not identified. Statistically, the efficacy is marginal at best… I don’t doubt the social and emotional value of dogs as companions, and as active helpers in many circumstances. But beyond this, the evidence is wanting.[18]

See also[edit]

References[edit]

  1. ^ "Can dogs smell cancer?". Dogs Detect Cancer - Saving Lives. Retrieved 13 February 2015. 
  2. ^ "Dogs to be used to detect breast cancer in new research trial". Telegraph.co.uk. 15 August 2014. Retrieved 13 February 2015. 
  3. ^ http://www.huffingtonpost.com/entry/cancer-sniffing-dogs_us_55ed354de4b093be51bbc4bc
  4. ^ Saul, Heather (3 August 2016). "Shannen Doherty says her dog detected her cancer". The Independent. Retrieved 18 December 2016. 
  5. ^ Langley, Liz (19 March 2016). "How Dogs Can Sniff Out Diabetes and Cancer". National Geographic News. Retrieved 18 December 2016. 
  6. ^ Chodosh, Sara (5 October 2016). "The Problem With Cancer Sniffing Dogs". Australian Popular Science. Retrieved 18 December 2016. 
  7. ^ Marucot, Joyce (29 September 2016). "Dogs Can Smell Fear But Can't Detect If You Have Lung Cancer". Nature World News. Retrieved 18 December 2016. 
  8. ^ http://www.nbcnews.com/nightly-news/video/these-dogs-are-using-their-noses-to-sniff-out-prostate-cancer-520407107854
  9. ^ Williams H, Pembroke A (1989). "Sniffer dogs in the melanoma clinic?". Lancet. 1 (8640): 734. PMID 2564551. doi:10.1016/S0140-6736(89)92257-5. 
  10. ^ Church J, Williams H (2001). "Another sniffer dog for the clinic?". Lancet. 358 (9285): 930–930. PMID 11575380. doi:10.1016/S0140-6736(01)06065-2. 
  11. ^ Willis CM, Church SM, Guest CM, et al. (2004). "Olfactory detection of human bladder cancer by dogs: proof of principle study". BMJ. 329 (7468): 712–0. PMC 518893Freely accessible. PMID 15388612. doi:10.1136/bmj.329.7468.712. 
  12. ^ "USATODAY.com - Study shows dogs able to smell cancer". usatoday.com. Retrieved 13 February 2015. 
  13. ^ "Dogs Can Smell Cancer". cbsnews.com. 24 September 2004. Retrieved 13 February 2015. 
  14. ^ McCulloch M, Jezierski T, Broffman M, Hubbard A, Turner K, Janecki T (2006). "Diagnostic accuracy of canine scent detection in early- and late-stage lung and breast cancers". Integrative cancer therapies. 5 (1): 30–9. PMID 16484712. doi:10.1177/1534735405285096. 
  15. ^ Ehmann R, Boedeker E, Friedrich U, et al. (August 2011). "Canine scent detection in the diagnosis of lung cancer: Revisiting a puzzling phenomenon". Eur Respir J. 39 (3): 669–76. PMID 21852337. doi:10.1183/09031936.00051711. 
  16. ^ "Dogs Smell Cancer in Patients' Breath, Study Shows". National Geographic News. 12 January 2006. Retrieved 31 August 2011. 
  17. ^ "BBC NEWS - Health - Lung cancer 'colour breath test'". bbc.co.uk. Retrieved 13 February 2015. 
  18. ^ a b Lipson, Peter. "What to make of Medical Dogs". Sciencebasedmedicine.org. Retrieved 5 October 2016. 

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