Cancer stinks, but maybe that's OK

[Rich_by_the_Bay]

Sorry this excerpt is so long, but it is both interesting and important. Caution: do not read this before a meal...

Bottom line: dogs can sniff out colon cancer. Quite well, it appears.

Sonoda H, Kohnoe S, Yamazato T, et al. Colorectal cancer screening with odour material by canine scent detection. Gut. 2011 Jun;60(6):814-9.

Abstract
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.
​

 

[REWahoo]

I can see it now...

Doc (snapping on surgical glove): "Please drop your trousers and bend over."
Patient: "I really hate this part of the exam."
Doc: "I understand, but we just haven't figured out a good way to warm Fido's nose."

 

[TromboneAl]

I know it sounds weird, but I wonder if anyone has tried it with human scent detection (you though you hated your job). But seriously, check out this:

http://www.early-retirement.org/forums/f27/mysterious-house-smell-51473.html#post965673

 

[ERD50]

Thanks for posting - very interesting. I recall reading about this years ago. Maybe they were just training the dogs then, and this study is the result?

Rich, can you decode this for us:

The sensitivity of canine scent detection ... was 0.97 and the specificity was 0.99.

Does that mean the dogs could correctly detect 97 out of 100 cancer samples, and would give a false positive in 1 out of 100?

What would be the incidence in a population that you would be screening for CRC? If my assumption above is correct, and (just for example) if 1% of the population being screened actually had detectable CRC, that could mean:

(based on my pulled-from-air numbers/assumption) For 10,000 screened, there would be 100 with detectable CRC, the dogs would correctly ID 97 of them, and falsely ID 100 people that had no CRC. Even though it doesn't seem so great when I put it that way, I guess it means only 200 would go on to more aggressive screening, rather than all 10,000?

-ERD50

 

[Rich_by_the_Bay]

Thanks for posting - very interesting...
Rich, can you decode this for us:

Does that mean the dogs could correctly detect 97 out of 100 cancer samples, and would give a false positive in 1 out of 100?

Sensitivity = the probabilitiy on a zero-to-one scale that a patient with colon cancer will have an abnormal result on this test.

Specificity = probability (0-to-1) that patients who do not have colon cancer will have a negative (normal) test result.

False positive rate = (1 - specificity)

False negative rate = (1 - sensitivity)

 

[packrat44]

Doing it "doggy style" takes on a whole new meaning.

 

[Alan]

PET scans are getting better.

 

[Rich_by_the_Bay]

PET scans are getting better.

CAT scans, too.

 

[palomalou]

Wow! This is particularly interesting because I've pondered why my internist is an eerily good diagnostition. One of my surgeons asked me why suddenly the internist ordered a colonoscopy which diagnosed colon cancer--years before it would be "due." My conclusion, only half in jest, has been that he SMELLS illness. Of course, all sorts of tests are run, but he picks up things not in the test results.

 

[Dawg52]

Should I be nervous next time my dog takes a good sniff of my behind and passes out?

 

[GregLee]

I suppose we can assume that the dog handler and all spectators were ignorant of which boxes held the cancer prize.

Not to diminish at all the interest of this result, it may be relevant to mention doubts about the usefulness of early detection and treatment. Probably because some cancers that are detected early are very slow growing, finding them may not extend life, and treating them then exposes patients to side effects of medications for no real benefit.

 

[Texas Proud]

I remember reading something similar a long time ago....

There was a "problem" with the dog since he would sit next to a control sample... they could not figure out why.... until later it was determined that the person actually HAD cancer that was undetected at the time...

 

[Rich_by_the_Bay]

There are melanoma-sniffing dogs reported as well, but not researched as rigorously as in the current study.

 

[kumquat]

CONCLUSIONS: .....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.
​

Why not just train a few more dogs?

 

[Zero]

as someone who loves the heck out of dogs snf love with those little critters. I would be happy to see every one of them trained, loved and put to work sniffing butts.

They would be so happy to do whatever they were tasked.

 

[Walt34]

as someone who loves the heck out of dogs snf love with those little critters. I would be happy to see every one of them trained, loved and put to work sniffing butts.

Yeah, talk about loving your work. Those dogs would never want to retire....

 

[TromboneAl]

Break time!

 

[samclem]

Why not just train a few more dogs?

Because a gazilion dollar biotech startup can't be launched that way?

 

[landover]

Why can't this kind of machine designed for diagnosis, not much incentive, not much payback, smell is too complex for current technology?



IONSCAN SENTINEL II

also interesting - http://www.nytimes.com/2011/01/04/health/04tb.html

 

[samclem]

Why can't this kind of machine designed for diagnosis, not much incentive, not much payback, smell is too complex for current technology?

I'm not sure, but last I'd heard current technology couldn't match a pooch for sniffing out bombs, drugs, etc.

 

[TromboneAl]

I've just realized that this study is only meant to show that "a specific cancer scent does indeed exist and that cancer-specific chemical compounds may be circulating throughout the body" and isn't meant to suggest that this will ever be used for diagnosis in a clinical setting.

That's a very useful thing to know, and means that working on a machine that could detect these odors is a worthwhile endeavor.

In any case, there's no way that a self-respecting physician is going to tell a patient that his stool sample will be sent off and a dog will smell it to check for cancer.

 

[ERD50]

In any case, there's no way that a self-respecting physician is going to tell a patient that his stool sample will be sent off and a dog will smell it to check for cancer.

Well, I would respect him/her if the evidence backs up the method.


Seems I've been reading more and more that docs are following various procedures that are not evidence based (were stents an example - sound good, but the evidence did not back it up?). I don't respect that, and they shouldn't either.

Anyhow, they would wrap a fancy name around it - ' we will be sending your sample to our new, modern, biogeneic, olfactory analysis laboratory' , sounds a lot better than 'send it to a lab(rador) in a kennel'

-ERD50

 

[Nords]

There are melanoma-sniffing dogs reported as well, but not researched as rigorously as in the current study.

You'll have to keep us up-to-date on the cancer-sniffing dogs for the prostate and breast areas, too.

In any case, there's no way that a self-respecting physician is going to tell a patient that his stool sample will be sent off and a dog will smell it to check for cancer.

Medicare is now offering higher reimbursement rates for diagnostic code "K9"...