The Institute of Physics is publicizing a novel finding presented at their annual conference: a highly sensitive way to diagnose and stage cancer.
Professor Käs’ technique for the first time uses a physical characteristic of each cell – its stretchiness or elasticity – instead of its biological make-up, to decide whether or not it’s cancerous. Cancer cells tend to de-differentiate, losing the special characteristics of the organ where they started life. Because of this, they no longer need the rigid cytoskeleton which holds them in shape, making them stretchier than normal cells.
Käs and Guck’s machine uses a powerful beam of infrared laser light to stretch and measure cells one by one. His optical stretcher differs from an existing tool known as optical tweezers in which the light is focused to a sharp point to grab hold of a cell..
“Of all the physical properties of a cell,” explains Professor Käs, “elasticity is the one which varies most dramatically between normal and cancerous cells.” This makes stretching the most sensitive method known for identifying cancer. Just 50 tumour cells are needed in a sample for the optical stretcher to diagnose cancer, contrasting with traditional methods which need 10,000 to 100,000 cells. With such small samples, diagnoses can be made even before solid tumours develop, or where a traditional biopsy is problematic.
More importantly, the optical stretcher can yield crucial information on the spread of cancer. The softer the cancer cells, the more likely they are to travel through the body and produce secondary tumours (known as metastases). Traditionally, doctors have had to check nearby lymph nodes for cancer cells. However, the optical stretcher can determine, just by measuring cells from the primary tumour, whether or not the cancer will spread. This is the first time that anyone has been able to diagnose metastasis without locating the secondary tumours.
One of us used to work with cytoskeletons and can vouch that cells can indeed vary their stretchability. Very clever! But we also know that metastases can occur through a variety of molecular mechanisms, some that don’t involve cell deformation.
Also, one of the designers is talking about a sea change in cancer prevention, but the use of this device in screening seems limited to swabbable areas. For the vast majority of tumors, we’ll probably have to wait for lumps, symptoms, or imaging to reveal something.
More at the website of Professors Käs and Guck.
