New test improves cancer diagnosis
 |  Using an "optical stretcher," cancer clinics would be able to make a cancer diagnosis from as few as 50 cells. |
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LEIPZIG, Germany -- A new technique that measures the elasticity of cells could revolutionize cancer detection and remove most of the guesswork in predicting if tumors are likely to spread.
The system, which uses a machine as small as a laptop, can provide a diagnosis from as few as 50 cells, avoiding the need to cut out tissue for testing.
Its relatively low cost means in future it could become a standard item of equipment in surgeries, and may even be used by dentists.
The technique is said to be 1,000 times more accurate than the most sensitive traditional tests. But its biggest advantage is that it can identify cancers that are about to spread.
Usually a spreading, or metastatic, cancer can only be identified once it has actually moved from its primary site. Normally it is detected in the lymph nodes.
The new system could allow doctors from the outset to spot patients at high risk of metastatic cancer, and tailor their treatment accordingly.
It could, for instance, avoid the risk of removing a woman's breast to stem the spread of cancer when such drastic treatment is not necessary.
The technique, developed by Professor Josef Kas and Dr. Jochen Guck, from the University of Leipzig in Germany, uses a laser-operated "optical stretcher" to measure the physical strength of individual cells.
Cancer cells differ from normal cells in that they are softer and more elastic.
Those that are likely to spread are especially "stretchy". By detecting these elastic cells within a sample the test can not only diagnose cancer but also determine the chances of metastasis.
"Of all the physical properties of a cell, elasticity is the one which varies most dramatically between normal and cancerous cells," Professor Kas told the UK's Press Association.
"This technique can make a diagnosis of cancer from as few as 50 abnormal cells. Usually you need between 10,000 and 100,000 cancer cells before you can say with certainty that a patient has cancer.
"It is three orders of magnitude more sensitive than any existing technique and a revolutionary step forward."
Cells for testing can be removed by means of a fine needle inserted at about 10 points around the site of a suspect tumor in a procedure more like acupuncture than a traditional biopsy.
The cells are placed in the "optical stretcher" which passes a powerful beam of infrared laser light through them.
As the light enters and leaves each cell, it is given a "kick" and stretched by a minute degree. From this, the cell's elasticity can be calculated.
"If we find a tumor, the degree of stretchiness in the cells allows us to identify sub-populations of cells which are very close to becoming metastatic, and others that have full metastatic potential," said Kas.
The optical stretcher can test as many as 3,600 cells per minute, so is already fast enough to be useful in diagnosis, he said.
A small proof-of-principle study of about 30 breast cancer patients at Leipzig University had already yielded very promising results.
The "optical stretcher" accurately identified which patients had metastatic cancer and provided much more information besides. Kas is now looking for an industrial partner to manufacture a prototype for full clinical trials.
Kas envisioned the test being used routinely by consultants, and also dentists, who could simply take a swab of saliva from a patient's mouth to check for signs of oral cancer.
The same technique can also be used in a different way to filter out valuable stem cells in blood, he said.
Currently "haematopoietic" stem cells have to be harvested from bone marrow. They are unprogrammed cells that normally develop into blood or immune cells, but also have the potential to become heart tissue and nerves.
Stem cells are even more elastic than cancer cells, making it possible to identify them using the "optical stretching."
"Potentially it means we could obtain haematopoietic stem cells from donated blood," he said.
However more work was first needed to speed up the process, he added.
