Published in the journal iScience, the new study reveals that the insects are able to differentiate between cancerous and healthy cells, as well as between different types of cancers, after just 30 minutes of training.
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The development of non-invasive and cost-effective techniques to detect cancer is a major public health challenge, which is why scientists have begun enlisting the help of animals with sensitive noses. This is because cancer cells have an altered metabolism that results in the production of certain volatile organic compounds (VOCs), which can be sniffed out by species with sufficiently sophisticated olfactory apparatus.
Dogs, for instance, are excellent at detecting VOCs, which is why they are often called upon to help diagnose diseases or to identify hidden narcotics and other illicit items. However, the study authors explain that “despite being efficient, [dogs] are slow to learn… and require an intensive learning protocol before being ready to discriminate cancer samples from a healthy one.â€
At the same time, they state that ants are “equivalent to dogs… in terms of detection abilities,†and that the insects can be trained in a matter of minutes to perform tasks that canines may need a whole year to learn.
The researchers sought to train a species of ant called Formica fusca to detect cancerous cells. To achieve this, they placed breast cancer cells in a petri dish along with healthy cells, yet added a sugary treat next to the cancerous cells.
Over successive trials, the ants got quicker and quicker at finding the treat, indicating that they had learned to recognize the VOCs produced by the cancerous cells, using these as a beacon to guide their way to the sugary delight. After conducting this trial just three times, the researchers decided to repeat the experiment without adding the treat, and found that the insects continued to make a bee-line for the cancerous cells, suggesting that they remembered the smell of these cells and the previous association with the sugary reward.
The study authors then put the ants through the same training protocol, yet this time included two different types of breast cancer cells. As with the first experiment, one of these cells lines was accompanied by a sugar treat while the other was not.
Once again, the ants quickly learned to move directly towards the cancer that was associated with the reward, indicating that they were capable of distinguishing between the different cancer types based on the unique pattern of VOCs emitted by each one.
Summarizing their findings, the authors state that “ants were able to i) perceive the presence of cells in a medium, ii) differentiate cancerous VOCs from non-cancerous ones, and iii) differentiate between two cancerous samples based on VOCs.†■