Ants can 'sniff out' cancer tumors in urine, says new study

The researchers taught the ants to link the scent of tumors with a reward by dabbing a drop of sugar into the water.
Nergis Firtina
Formica fusca.
Formica fusca.

FrankRamspott/iStock 

A newly published study has announced that ants can detect cancer tumors by smell, thanks to their strong olfactory receptors. Published in the journal Proceedings of the Royal Society B: Biological Sciences this week, the study shows Formica fusca ants are able to detect tumors by smelling patients' urine, as reported by The Independent.

"Ants can be used as bio-detectors to discriminate healthy individuals from tumor-bearing ones," says Patrizia d'Ettorre, co-author of the study and a scholar at the Sorbonne Sorbonne Paris North University. "They are easy to train, learn fast, are very efficient, and are not expensive to keep," she added.

On the other hand, Scientific American underlines volatile organic compounds, which are released specifically by cancerous tumors, are frequently found in physiological fluids, including perspiration and urine, as well as in breath vapor.

How was the process?

The study's lead author, Baptiste Piqueret, an ethologist at Sorbonne Paris North University, and his team began by xenografting human breast cancer tumors into mice and allowing them to develop. Then they took urine samples from healthy and tumor-ridden animals.

The researchers taught the ants to link the scent of tumors with a reward by dabbing a drop of sugar water in front of the urine from cancer-stricken mice. The flies lingered near the urine of malignant mice for roughly 20 percent longer than that of healthy mice when the team withdrew the sugar water because they were seeking a tasty treat.

Ants can 'sniff out' cancer tumors in urine, says new study
Silky ant (Formica fusca).

The ants' smell association was established in just three training sessions or around 10 minutes overall. That's a lot quicker than, say, training canines to detect cancer, which can take up to six months.

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In addition to Piqueret's words, "We trained them with associative learning to associate a given odor – cancer – with a reward and, after very few trials, they learned the association," said d'Ettore.

"We demonstrated that ants can discriminate the urine of healthy mice from the urine of tumor-bearing mice. This is more similar to a real-life situation than using cultured cancer cells. We were surprised by how efficient and reliable the ants are," she added, as per The Independent.

More about Formica fusca

A black ant known as Formica fusca is widespread throughout Europe, as well as in some regions of Southern Asia and Africa. Its popular names include silky ant and dusky ant. The Palaearctic region's range stretches from Italy in the south to Fennoscandia in the north and from Portugal in the west to Japan in the east.

Using a classical conditioning strategy, workers of this ant species can learn to link an olfactory signal to a reward (a sugar solution). Ants are quick learners; all it takes for them to develop a true long-term memory is one presentation of the stimuli. Additionally, this created memory is extinction-resistant.

The study is published in the journal Proceedings of the Royal Society B: Biological Sciences.

Study abstract:

Early detection of cancer is critical in medical sciences, as the sooner a cancer is diagnosed, the higher are the chances of recovery. Tumour cells are characterized by specific volatile organic compounds (VOCs) that can be used as cancer biomarkers. Through olfactory associative learning, animals can be trained to detect these VOCs. Insects such as ants have a refined sense of smell, and can be easily and rapidly trained with olfactory conditioning. Using urine from patient-derived xenograft mice as stimulus, we demonstrate that individual ants can learn to discriminate the odour of healthy mice from that of tumour-bearing mice and do so after only three conditioning trials. After training, they spend approximately 20% more time in the vicinity of the learned odour than beside the other stimulus. Chemical analyses confirmed that the presence of the tumour changed the urine odour, supporting the behavioural results. Our study demonstrates that ants reliably detect tumour cues in mice urine and have the potential to act as efficient and inexpensive cancer bio-detectors.