January 17, 2006
|Dogs Trained To Detect Cancer By Smell With 99% Accuracy||Science/Technology|
California clinicians have trained five dogs to detect cancer by sniffing the breath of patients. The remarkable thing is that the reported accuracy is better than any lab test. NYT:
In the small world of people who train dogs to sniff cancer, a little-known Northern California clinic has made a big claim: that it has trained five dogs — three Labradors and two Portuguese water dogs — to detect lung cancer in the breath of cancer sufferers with 99 percent accuracy.
The study was based on well-established concepts. It has been known since the 80's that tumors exude tiny amounts of alkanes and benzene derivatives not found in healthy tissue.
Other researchers have shown that dogs, whose noses can pick up odors in the low parts-per-billion range, can be trained to detect skin cancers or react differently to dried urine from healthy people and those with bladder cancer, but never with such remarkable consistency.
The near-perfection in the clinic's study, as Dr. Donald Berry, the chairman of biostatistics at M. D. Anderson Cancer Center in Houston, put it, "is off the charts: there are no laboratory tests as good as this, not Pap tests, not diabetes tests, nothing."
As a result, he and other cancer experts say they are skeptical, but intrigued. Michael McCulloch, research director for the Pine Street Foundation in Marin County, Calif., and the lead researcher on the study, acknowledged that the results seemed too good to be true. (For breast cancer, with a smaller number of samples, the dogs were right about 88 percent of the time with almost no false positives, which compares favorably to mammograms.)
"Yes, we were astounded, as well," Mr. McCulloch said. "And that's why it needs to be replicated with other dogs, plus chemical analysis of what's in the breath." [...]
In Mr. McCulloch's study, the five dogs, borrowed from owners and Guide Dogs for the Blind, were trained as if detecting bombs. They repeatedly heard a clicker and got a treat when they found a desired odor in many identical smelling spots. [...]
"The fact that dogs did this is kind of beside the point," he said. "What this proved is that there are detectable differences in the breath of cancer patients. Now technology has to rise to that challenge."
The next step, he said, will be to analyze breath samples with a gas chromatograph to figure out exactly which mixes of chemicals the dogs are reacting to. [Emphasis added]
I love these low-tech solutions.