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This is pretty freaking cool!
Dogs trained to sniff out bladder cancer
00:01 24 September 04
NewScientist.com news service
Dog walkers know the canine habit of sniffing lampposts for urine only too well. Now, in a novel experiment, a team of scientists and dog trainers have put this traditional canine behaviour to good use – sniffing human urine to detect bladder cancer sufferers.
The researchers hope that analysis and identification of the characteristic chemical odorants may lead to non-invasive, early-detection screening methods for bladder cancer in the future.
“There had been a series of anecdotal stories about patients whose pet dogs had aroused concern by continually sniffing their moles, which actually turned out to be cancerous. I was pretty sceptical and needed to design a simple experiment to test it,” explained the study’s lead author, Carolyn Willis, from Amersham Hospital in the UK.
The impracticalities of training dogs to detect skin cancer using skin biopsies led Willis and colleagues to consider trying bladder cancer detection, using easily obtainable urine samples. The group used urine samples from 36 patients with bladder cancer, and 108 control samples from cancer-free individuals.
Six dogs of varying ages and breeds underwent a seven month training course in cancer detection, carried out by trainers from Hearing Dogs for the Deaf.
Blood and proteins
“We wanted to make sure it was the cancer they were smelling, so we ruled out other urine abnormalities by having control samples with blood, proteins, leukocytes and other abnormalities by using urine from patients with non-cancerous urological disorders,” Willis said.
The dogs were trained to lie down in front of the urine sample from a cancerous bladder (Image: Hearing Dogs for Deaf People)
In the final, double-blind experiment, each dog underwent nine separate tests in which they were shown an array of seven urine samples, one of which was cancerous, and told to lie down next to the cancerous one. The dogs correctly identified the cancer sample on 22 out of 54 occasions. This success rate of 41% is much higher than the 14% expected from chance alone.
The researchers suspect that the dogs were detecting a specific profile of aromas linked to the abnormal metabolic products of cancer cells. These volatile organic chemicals may include alkanes and alkenes, they believe.
“At the moment, the dogs’ accuracy rate, while statistically significant, is nowhere near accurate enough for diagnostic testing, and it would be impractical anyway,” Willis told New Scientist. “But if we can identify the pattern of chemicals the dogs are detecting, we could work towards a screening process for bladder cancer.”
During the experiment, one of the control samples was consistently identified by the dogs, despite the donor patient having tested negative for bladder cancer. The surgeon was so impressed by the dogs, however, that the patient was tested again and found to have a kidney tumour.
Bladder cancer is a particular risk to people over the age of 65, and men have three times the risk of women. It is detected using cystoscopy – inserting a fibre-optic instrument into the bladder via the urethra. Since it commonly recurs, patients who survive the cancer must undergo regular cystoscopy as a form of screening.
This is pretty freaking cool!
Dogs trained to sniff out bladder cancer
00:01 24 September 04
NewScientist.com news service
Dog walkers know the canine habit of sniffing lampposts for urine only too well. Now, in a novel experiment, a team of scientists and dog trainers have put this traditional canine behaviour to good use – sniffing human urine to detect bladder cancer sufferers.
The researchers hope that analysis and identification of the characteristic chemical odorants may lead to non-invasive, early-detection screening methods for bladder cancer in the future.
“There had been a series of anecdotal stories about patients whose pet dogs had aroused concern by continually sniffing their moles, which actually turned out to be cancerous. I was pretty sceptical and needed to design a simple experiment to test it,” explained the study’s lead author, Carolyn Willis, from Amersham Hospital in the UK.
The impracticalities of training dogs to detect skin cancer using skin biopsies led Willis and colleagues to consider trying bladder cancer detection, using easily obtainable urine samples. The group used urine samples from 36 patients with bladder cancer, and 108 control samples from cancer-free individuals.
Six dogs of varying ages and breeds underwent a seven month training course in cancer detection, carried out by trainers from Hearing Dogs for the Deaf.
Blood and proteins
“We wanted to make sure it was the cancer they were smelling, so we ruled out other urine abnormalities by having control samples with blood, proteins, leukocytes and other abnormalities by using urine from patients with non-cancerous urological disorders,” Willis said.
The dogs were trained to lie down in front of the urine sample from a cancerous bladder (Image: Hearing Dogs for Deaf People)
In the final, double-blind experiment, each dog underwent nine separate tests in which they were shown an array of seven urine samples, one of which was cancerous, and told to lie down next to the cancerous one. The dogs correctly identified the cancer sample on 22 out of 54 occasions. This success rate of 41% is much higher than the 14% expected from chance alone.
The researchers suspect that the dogs were detecting a specific profile of aromas linked to the abnormal metabolic products of cancer cells. These volatile organic chemicals may include alkanes and alkenes, they believe.
“At the moment, the dogs’ accuracy rate, while statistically significant, is nowhere near accurate enough for diagnostic testing, and it would be impractical anyway,” Willis told New Scientist. “But if we can identify the pattern of chemicals the dogs are detecting, we could work towards a screening process for bladder cancer.”
During the experiment, one of the control samples was consistently identified by the dogs, despite the donor patient having tested negative for bladder cancer. The surgeon was so impressed by the dogs, however, that the patient was tested again and found to have a kidney tumour.
Bladder cancer is a particular risk to people over the age of 65, and men have three times the risk of women. It is detected using cystoscopy – inserting a fibre-optic instrument into the bladder via the urethra. Since it commonly recurs, patients who survive the cancer must undergo regular cystoscopy as a form of screening.
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