During the Covid lockdown in France, doctoral student Baptiste Piqueret, who was studying at the Sorbonne in Paris, conducted a series of remarkable experiments in his apartment. He had already laid the groundwork showing that silky ants – Formica fusca – have a refined sense of smell and are also able to learn different odours rapidly and then remember these. His lockdown experiments have just been published in Proceedings of The Royal Society B: Biological Sciences and show that ants can be trained to detect breast cancer (see cartoon above right, © Washington Post).
Piqueret makes the point that early detection of breast cancer is critical because the sooner a tumour is diagnosed, the greater are the chances of successful treatment and recovery. “Tumour cells are characterized by specific volatile organic compounds (VOCs) that can be used as cancer biomarkers,” he said. Insects such as ants have a refined olfactory system and can be easily trained to detect these VOCs.
Piqueret, who had been fascinated by ants (seen left, © Washington Post) during his childhood in rural France, and had played with them, knew that these insects used their sensory appendages on top of their heads to detect chemical cues to accomplish a range of tasks. These included protecting their young, finding food, and identifying colony mates. This form of chemical communication enables ants to build complex societies, so that queens and workers operate in synchrony using a sophisticated sense of smell.
Piqueret grafted human breast cancer tumours onto mice and then trained 35 ants to associate urine from the xenografted rodents with sugar. When the ants were placed in a petri dish, they spent significantly more time near the tubes with urine from “cancerous” mice compared with urine from healthy mice. “The results are very promising,” said Piqueret, although he added: “It’s important to know that we are far from using them as a daily way to detect cancer.”
The next step for Piqueret (seen right) and his collaborators will be to see whether the ants are able to detect the biomarkers for breast cancer in the urine from actual patients. The young scientist obviously has a good sense of humour, saying that if ants are ever used to screen for breast cancer, “They will not need to crawl on you. There will be no contact between ants and people.” He is optimistic ants have the potential to act as efficient and inexpensive cancer biomarkers, but of course imaging systems will always be required to identify exactly where the tumour is located.