A simple coin-sized device might be the latest in technology to detect even early stages of lung cancer, say American researchers.
The colorimetric sensor developed by Dr. Peter Mazzone and his team from Cleveland Clinic and the company ChemSensing of Illinois has 36 color dots that change color when a person with lung cancer exhales on to it.
The principle behind this is quite simple, though the technology is not.
Tumorous growths or cancer cells in the lung release some volatile organic chemicals. These are passed into the air that leaves the diseased lungs. These compounds then interact with the different chemicals in the sensor and elicit color changes in them.
The researchers tested the device on 143 persons with lung cancer, other lung disorders and persons with healthy lungs. They were asked to use the device for 12 minutes.
The test was able to detect around 75 percent of the cases of lung cancer. Yet there were false positives too. In spite of this, Mazzone says, "Ultimately, this line of investigation could lead to an inexpensive, non-invasive screening or diagnostic test for lung cancer."
Catching lung cancer early, when it is still treatable, could save tens of thousands of lives a year in the United States alone. It is the most common form of malignant cancer and also kills the most people, partly because it is not usually detected until it has spread.
So far, the most accurate detector of cancer has been dogs.
In 2006, researchers found dogs could be trained to smell cancer on the breath of patients with 99 per cent accuracy.
Dr. Jesme Fox, medical oncologist and medical director at the Roy Castle Lung Cancer Foundation, has welcomed the invention "There is a desperate need to get people diagnosed earlier.
"At the moment we rely on people coming forward with symptoms, or a suspect chest x-ray picked up purely by chance."
In the past, scientists have used highly sensitive machines such as gas chromatography and mass spectroscopy to "read" the volatile organic compounds coming from diseased lungs.
But the machines are expensive to use and require specially trained experts to interpret the results.
In comparison, the color sensor is cheap and easy to read, according to the researchers who published their report in Thorax.