Low and High-Tech ‘Noses’ Sniff Out
June 28th, 2015 by Holly Cornish
Daisy repeatedly pawed at Clair Guest’s chest. This behavior towards her owner was totally out of character.
“I felt the tender area where she’d pushed me, and over the next few days I detected the tiniest lump.”
Although the lump turned out to be a harmless cyst, “further in the breast tissue was a deep-seated cancer.” The incident provides more proof of what many experts have known for a while: Dogs have the ability to sniff out cancers – and this fact can be a lifesaver. . .
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Because it was caught early, conventional treatment resolved Clair Guest’s problem. Had she waited until it became noticeable, she might not have been so lucky.
Daisy the Labrador is now one of a team of cancer detection dogs that are showing great promise in sniffing out compounds that are specific to a wide range of cancers.
Sniffing out melanoma
It’s ironic that Dr. Guest’s own dog helped save her from cancer, because five years earlier she was involved with one of the first studies to test whether dogs can detect cancer. “Animal behavioral psychologist” is her job title.
In this ‘proof of principle’ study, six dogs were accurate in detecting, by way of urine samples, 22 out of 54 cases of bladder cancer. The dogs achieved a 41% success rate, compared to 14% that would have been expected by chance alone.
Dr. Guest was inspired to get involved in this work when she heard the story of Gillian Lacey.
Her pet Dalmatian Trudii became agitated by what looked like a harmless freckle on Gillian’s right leg. The animal kept sniffing and nibbling at it. Months went by before Gillian visited her doctor, who diagnosed the lesion as malignant melanoma. After successful surgery, the dog took no further interest in her leg.
Dr. Guest went on to create Medical Alert Assistance Dogs who live with owners affected by serious conditions that could be life threatening. Dogs are able to detect when cortisol or blood sugar levels get too low (Addison’s disease and type 1 diabetes respectively), as well as identifying the odor of peanuts in food for people with nut allergies.
Dr. Guest hopes the fifteen cancer detection dogs on her team will act as a second-line screening tool to revolutionize early diagnosis.
A dog’s nose is very sensitive
While humans have five million scent glands, dogs have up to 300 million, depending on the breed. Just as they can be trained to sniff out drugs or explosives, their sensitive noses can detect other odors in concentrations as low as one part in a trillion.
Dr. Guest pursues her research in the UK, but dogs are also trained to detect cancer in the United States and other countries. Currently the animals only take part in research trials. They are trained by sniffing urine, stool, blood and tissue specimens as well as breath samples preserved on a fiber filter.
Since the early studies, training has become more sophisticated and the dogs’ detection abilities have improved — as demonstrated by two examples reported in 2015. The first is from Italian researchers.
Testing dogs’ ability to detect prostate cancer
Two German shepherds previously trained to detect explosives were recruited to identify ‘volatile organic compounds’ in the urine of prostate cancer patients.
For the study, the dogs had to sniff 362 samples provided by men with confirmed diagnosis and 540 samples of a control group of adults without prostate cancer. The control group consisted of men and women who were either healthy or had various health problems including other forms of cancer.
The study was blinded so that the handlers giving the dogs samples to smell did not know whether they were from prostate cancer patients or the control group.
Results were impressive. One dog achieved 100% and the other 98.6% sensitivity, (correctly identifying those with the disease). The dogs also attained 98.7% and 97.6% specificity, (correctly identifying those without the disease). False positives and false negatives were therefore kept to very low levels.
Since the PSA test used to initially detect prostate cancer is highly unreliable, submitting samples of suspected cases before two or more dogs could be a dependable second stage screening tool.
Dr. Guest explains, “Prostate biopsy is very painful and there are infection risks. This could really help a doctor making a decision about whether to take a biopsy or not.”
Frankie sniffs out thyroid cancer
The second example is from a group at the University of Arkansas led by Donald Bodenner, M.D., Ph.D., chief of endocrine oncology, who reported their findings at the annual Endocrine Society meeting.
Frankie the German shepherd, after six months training, was presented with 34 urine samples. These came from people who had sought treatment at a thyroid clinic because they had two or more nodules that posed a cancer risk.
Frankie gave his diagnosis before the pathology laboratory reported its findings.
Frankie was accurate in 30 of the 34 samples with a sensitivity of 86.6% and specificity of 89.5%.
Dr Bodenner commented that “Current diagnostic procedures for thyroid cancer often yield uncertain results, leading to recurrent medical procedures and a large number of thyroid surgeries performed unnecessarily.
“Based on preliminary data, scent detection by trained canines serves as a noninvasive, inexpensive and highly specific adjunct to current diagnostic practices.
“If we can get sample numbers into the hundreds and still maintain a 90% accuracy, we’re probably going to be ready for prime-time, but that’s going to be several years from now.
“But it’s very doable. We have to get the statistics to convince people that this isn’t some stupid idea.”
Besides skin, prostate and thyroid cancers, dogs have also been trained to detect bladder, lung, breast, ovarian and colorectal cancers.
Some of the diagnostic results in these cancers have been very impressive.
For instance in 240 blood and tissue samples drawn from ovarian cancer patients and controls, two black Giant Schnauzers achieved a 100% sensitivity and 98% specificity in the blood and 99% and 97% sensitivity and specificity respectively in the tissues.
In colorectal cancer, of 185 stool samples, a Labrador retriever achieved a sensitivity of 97% and specificity of 99%.
In spite of the high rate of success achieved by sniffer dogs, not everybody is impressed. One leading oncologist said, “You can’t possibly have a dog in every doctor’s surgery [office], so I can’t see the relevance.” This strikes me as a foolish criticism because the fluid or tissue samples could be sent to a lab where the dogs are maintained, the same as testing is outsourced to other types of labs.
Cancer Research UK, with their characteristic conservatism towards any non-drug research, said that using dogs would not be practical.
The development of E-noses
Fortunately, for those in the medical profession who feel affronted that dogs with only months of instruction can be more successful at diagnosis than doctors, with their many years in medical school, technology has come to the rescue.
It is not known what the dogs are detecting. However, in many diseases there are specific volatile organic compounds in the breath that can be picked up with electronic sensors.
A number of these compounds, among hundreds, have been validated as markers of particular tumors. E-noses have been developed to detect these compounds in a range of cancers.
Michael Phillips, M.D., clinical professor of medicine at New York Medical College, has developed a device called BreathLink to detect breast cancer.
He said, ‘We know that if you get a negative result on the breast test, there is a better than 99.9% chance that a woman doesn’t have breast cancer.”
The device is not yet FDA approved, but Dr. Phillips hopes it will save the vast majority of women from having to undergo the trauma of a mammogram.
In Israel, developers are working with a different technology called the Nanoscale Artificial Nose to detect head and neck, ovarian and stomach cancers.
In a recent trial of 182 women with or without ovarian cancer, the e-nose was able to distinguish between them with 79% sensitivity and 100% specificity.
In another trial involving 484 people with or without stomach cancer, it achieved 73% sensitivity and 98% specificity.
In England, a team originating from Cambridge University has developed microchip technology – Field Asymmetric Ion Mobility Spectrometry – in an instrument called LuCID (Lung Cancer Indicator Detection).
It’s a small, low cost, portable device for detecting early stage lung cancer before any obvious symptoms appear. Results are available within seconds after breathing down a tube.
They hope doctors will use it routinely for patients at greater risk of the disease. They believe it has the potential to save 3,200 lives a year in the UK. It is currently undergoing trials. Results should be known in 2016.
Cancers such as lung, ovarian and stomach are usually only detected after they have spread. Screening in other cancers is often unreliable or not available. Convenient, non-invasive, low cost and accurate detection tools are urgently needed to catch cancers early and save lives.
While the use of dogs may be too eccentric for the conventional medical community to consider, e-noses are likely to become available and be used routinely within the next five or ten years.
Meanwhile — whether you’ve got cancer or you’re healthy and want to prevent it — you may wonder whether resveratrol is worth considering. I dug into that subject in the last issue, and if you missed it you can see it below.