Earlier this year, I speculated that electronic “noses” would someday be able to detect cancer. Now, I can report that we are getting closer (although trained dogs still seem better at the task!).
Background: It’s the second most common cancer for men worldwide, but prostate cancer remains difficult to diagnose, with standard blood tests criticized for delivering a high rate of false positives. But in a study presented in May this year, trained detection dogs were able to identify prostate cancer from a few sniffs of a urine sample with a staggering 98% accuracy, with few false positives. Although the study is by no means conclusive, it joins a growing body of research suggesting dogs could be able to smell out cancers.
However, there are numerous practical problems in using dogs to detect cancers in a medical setting (not least training, consistency and identifying exactly which chemicals the dogs are detecting), which is why scientists are seeking to harness the potential detection ability of man’s best friend through the development of an “electronic nose” capable of making a diagnosis.
Finnish researchers are using a device that conducts molecular analysis of the atmosphere in the “headspace” above urine samples, and tests it for the volatile organic compounds associated with prostate cancer. In a study published earlier this year, the method had a detection rate of 78%, and a specificity (the probability of the test being negative when cancer is absent) of 67%.
Researchers continue to refine the method, such as through removing impurities for cleaner sample analysis, but he believes the principle is reliable and can be applied to many other cancers.
“We have found there are over 30 molecule compounds in a tumor that are very smelly and easily sniffed. Eventually this can be used as a test for every cancer in the Western world,” he added.
Around the world, similar approaches are being applied to offer simple diagnosis for the world’s greatest killers. In 2011, the Gates Foundation announced funding for a battery-operated electronic nose prototype in India that functions as a breathalyzer test for tuberculosis.
The “NaNose” is being developed by the Israeli Technion Institute, claiming 90% accuracy in detecting lung cancer from a breath test, and providing enough information to distinguish between subtypes of the disease.
My Take: Dogs are still better, but I am confident that they will help to recognize diseases based on body odors. A dog recognizes thousands of odors at a time, so machines have a bit of learning to do to catch up. I’m Dr. Michael Hunter.
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