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The Prix Galien is widely recognized as medical technology’s equivalent of the Nobel Prize. In 2009, it was awarded to University of Twente researcher Leon Terstappen, whose ‘CellSearch Test’ finds cancer cells in the blood and identifies their exact properties. Therapy can then be tailored to the needs of the individual patient.

A tumour anywhere in the body can shed cancerous cells which enter the bloodstream. Some of these 'circulating tumour cells', or CTCs, can establish themselves elsewhere in the body and cause a secondary tumour. This process is known as metastasis. The original tumour, whether in the breast, prostate or large intestine, can be responsible for the spread of the disease through the entire body.

Although CTCs are clearly not welcome visitors, they do offer certain opportunities for patient treatment. Because blood can be drawn from the body very easily, the CTCs can be cultured to determine the exact nature of the original cancer. There are actually over one hundred types of cancer and it is very important to know the precise nature of the patient's cancer before starting therapy. The trick is to intercept the tumour cells individually and identify their properties.

And that is precisely what Prof. Leon Terstappen's CellSearch Test does. The system comprises two components: one which finds and 'flags' the CTCs in just 7.5 millilitres of blood, and one which analyses the cells. The CellSearch Test has drawn considerable interest from all over the world. In October 2009, Prof. Terstappen was awarded the American Prix Galien, the most prestigious honour in the field of medical technology, often referred to as the discipline's Nobel Prize.

The test relies on microscopic particles of iron which carry certain antibodies. In nature, those antibodies attach themselves to sick cells, whereupon the body's immune system will try to eradicate the defective cells. The antibodies will attach themselves to tumour cells but not to other, healthy cells in the blood. The tumour cells which have been 'labelled' in this way can be separated from the blood using a magnet. They are then brought into contact with yet more antibodies which are able to detect and reveal certain specific characteristics of the cancer cells. The various types of cancer cells are then counted. The resulting information enables doctors to determine which form of therapy is likely to be most effective.

Refining the technology
Leon Terstappen performed much of the research that would eventually lead to the CellSearch Test in the United States between 1994 and 2008. He is now head of the Medical Cell BioPhysics department of the University of Twente. The test is marketed by Veridex, an American subsidiary of the international pharmaceuticals group Johnson & Johnson.

Terstappen sees his main challenge to be refining the technology on which the groundbreaking test is based. He wishes to make it even more sensitive so that it can be used at an earlier stage of the disease. He is also trying to increase the number of cell characteristics that the test can identify. The CellSearch Test will then be even more effective in determining the most appropriate form of therapy for each individual patient.