A group of physicists out of the University of Leipzig, Germany, have developed a supersensitive cancer detection system, that uses a well known fact that the cytoskeleton (inner scaffolding) of cancer cells is more compliant than normal cell’s cytoskeleton.
When a laser beam from the device enters a cell, the light gains momentum because of the different conditions inside. According to the law of conservation of momentum, the cell must lose an equal but opposite amount, so its membrane bends towards the light source. “The cell gets a kick backwards,” explains Kas. When the laser light leaves the cell, it loses momentum and drags the cell’s opposite edge along with it. By applying a continuous beam, the cell gets stretched to its limit.
Without a strong cytoskeleton, cancerous cells are 40% easier to extend than their healthy counterparts. And cells from ‘metastasized’ tumours – those that have spread through the body – are an additional 30% more stretchy than early-stage cancer cells. This means that the laser could potentially assess how far the disease has advanced. “The softest ones are the most aggressive,” says Kas.
Currently, doctors cannot diagnose metastasis without discovering the location of the secondary tumours. The new laser-based method would pick up on metastasis based on cell elasticity alone, he says. In breast cancer, for example, the researchers believe this would mean fewer mastectomies carried out unnecessarily on the basis of guesswork about how far the disease has spread.
The test should be much more sensitive than cancer tests that simply use molecular markers to tag renegade cells. Kas explains that when cancer-causing genes begin to act in a cell they produce a small change in its structural proteins, but this has an exponential impact on elasticity. The underlying changes in the cell’s DNA, which are the focus of current cancer-detection methods, are nowhere near as dramatic.
Given a sample that contains at least 50 tumour cells, the laser can spot cancer more than 90% of the time, its creators claim. Nevertheless, further studies are needed to determine whether it can spot all types of cancer. “That will take years of testing,” says Kas, who presented the findings at a meeting of the Institute of Physics in Warwick, UK, this week.