Future Now
The IFTF Blog
The scent of . . . an illness
Most people know that dogs have a remarkable sense of smell that far surpasses our own. But did you know dogs can help sniff out cancer? This actually isn't a new story.
A 2006 study, published in the journal Integrative Cancer Therapies, and conducted by the Pine Street Foundation, a cancer research organization in San Anselmo, California, proved that dogs could detect breast cancer and lung cancer between 88 and 97 percent of the time. In a National Geographic report on the study, the executive director of the Foundation explained,
Canine scent detection of cancer was something that was anecdotally discussed for decades, but we felt it was appropriate to design a rigorous study that seriously investigated this topic to better evaluate its effectiveness. ... Cancer cells emit different metabolic waste products than normal cells. ... The differences between these metabolic products are so great that they can be detected by a dog's keen sense of smell, even in the early stages of disease.
The study leader commented, "Technology now has to rise to meet that challenge."
According to a New York Times article, that wish has finally come true. Scientists at the Israel Institute of Technology in Haifa have now developed what they say is an inexpensive, portable sensor technology that can quickly distinguish between the breath of lung cancer patients—which contains higher concentrations of alkanes and other volatile organic compounds—and healthy people. How does it work? The Times provides this brief explanation:
The sensor, described in Nature Nanotechnology, uses tiny particles of gold, five billionths of a meter in diameter, that are capped with organic compounds chosen for their ability to react with four of the volatile compounds found in higher concentrations in the breath of lung cancer patients. When the particles are deposited in a thin film between two electrodes, they act as an electrical resistor.
The researchers found that when an array of nine resistors was exposed to exhaled breath, the resistance changed as compounds in the breath reacted with the compounds on the gold particles. The patterns of the changes in the array differed depending whether the subjects had lung cancer or not.
You might think that would be the end of today's post: we've shifted from dogs's noses to nanotechnology's sensors. But wait, there's more.
Now rats are getting in on the action! It turns out that HeroRATS—aptly named rodents once trained by the organization, APOPO, to successfully detect landmines—are now being used for another important humanitarian detection application: TB diagnosis. According to a post in Global Health, in Tanzania, which has a high TB burden,
APOPO saw the potential of using rats to diagnose TB, and trained a small group of animals on the discrimination of TB positive sputa versus TB negative sputa. Whereas a trained lab technician can process a maximum of 40 sputum samples in a day, a HeroRAT can discriminate the same amount of samples in 7 minutes only! And HeroRATS can do this pretty reliably: in real world circumstances, a HeroRAT scent detection setup can diagnose pulmonary TB at 86 percent sensitivity and 89 percent specificity, or an overall reliability of 87 percent, compared to traditional sputum smear microscopy which reaches an alarming overall reliability of only 37 percent in Tanzania.
