Unlike existing techniques which rely on expert visual assessment or unreliable biochemical measurements, the "optical stretcher" tests the physical strength of each cell and can give a diagnosis using as few as 50 cells, allowing doctors to test for cancer where traditional biopsies are dangerous or even impossible. The ability to measure the progress of a cancer by examining only the primary tumour should reduce the number of unnecessary and traumatic mastectomies in women with breast cancer.

Professor Josef Ks and Dr Jochen Guck from the University of Leipzig have been developing the new procedure for several years and today described how the system is being tested, both to screen for oral cancers and in the "staging" of breast cancer tumours.

Professor Ks' 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.

Ks 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. In contrast, the optical stretcher doesn't use focused light. This allows laser beams strong enough to detect stretching to be used without killing the cell.

"Of all the physical properties of a cell," explains Professor Ks, "elasticity is the on
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Contact: David Reid
david.reid@iop.org
44-207-470-4815
Institute of Physics
11-Apr-2005