Physicians have known for a long time that a cancerous disease is also betrayed by scents: With their sensitive noses, dogs and mice, for example, can tell from body odor or urine samples from patients whether tumors are growing in the body. However, this is not suitable for a reliable diagnosis in practical cancer medicine – if only because dogs should be able to reliably recognize the smell of cancer, but in practice they get used to it and often get distracted. For several years now, a Japanese working group has been working on an alternative that is as suitable as possible for everyday medical use: cancer diagnosis with worms that are trained to smell tumors.
This is now making progress, reports a team led by Nari Jang from Myongji University in South Korea at the spring conference of the American Chemical Society. The team from South Korea also relies on the nematode, which is commonly kept in many biological laboratories Caenorhabditis elegans. C. elegans senses fragrances with a multitude of olfactory receptors and then meanders in the direction of more highly concentrated components.
In this way, the nematodes also react to the volatile compound 2-ethyl-1-hexanol, which smells flowery to humans. As the researchers were able to work out in experiments, ethylhexanols are, among other things, biological attractants from flowers, which use them to attract insects; but they are also produced, for example, by fungi to deceive. It is also known that lung cancer cells release 2-ethyl-1-hexanol; the threadworms can therefore recognize tumors from this substance. The cancer odor is also found in the urine of patients.
Jang’s team now wants to use their knowledge to develop a test kit that can be used in cancer medicine: a small, chip-like crawl space with branches for a few nematodes. These orient themselves in the direction of cancer cells or extracts and collect within an hour in the branch into which attractive test substrates are dripped. Healthy body cells, on the other hand, ignore the worms.