Device can spot cancer cells in blood: U.S. study

CHICAGO (Reuters) - A highly sensitive microchip may help doctors detect rare traces of cancer circulating in the bloodstream, offering a way to better manage treatment, U.S. researchers said on Wednesday.

The device can isolate, count and analyze circulating tumor cells from a blood sample, the team at Massachusetts General Hospital and Harvard Medical School in Boston said.

These circulating tumor cells, or CTCs, are the tiniest fragments of tumors, which are carried in the blood.

Doctors have known about them for some time, but because they are so rare and so fragile, they have been hard to trap and study in a meaningful way.

"What our technology does is increase the sensitivity many, many fold, to a point where it can become a tool that can be used clinically," said Mehmet Toner, whose group developed the device.

He said routine monitoring of these cells could help doctors tailor treatments to patients and may one day aid with diagnosis.

"Nine out 10 deaths in cancer are due to the metastatic process because the cancer spreads to other parts of the body," said Toner, whose study appears in the journal Nature.

"These are really the cells that end up killing people."

Current blood tests to detect these rare cells involved many steps of mixing and spinning and shaking, often killing what few cells they found.

"We went to the blackboard and designed it from scratch," Toner said in a telephone interview.

TRAPPING CANCER CELLS

The device they made uses a business-card sized silicon chip. It has microscopic posts that are coated with antibodies that recognize cancer cells.

As blood flows over the chip, these posts act like glue, trapping cancer cells and leaving blood cells behind.

Older methods may have produced one to five cells out of 60 billion cells screened in an 8-milliliter tube of blood. The new device can find 1,000 cancer cells.

The researchers tested their chip against blood samples from 68 patients with five types of tumors -- lung, prostate, breast, pancreatic and colorectal.

Out of 116 samples, they found circulating tumor cells in all but one sample, and none were found in samples taken from healthy people.

And the test was sensitive enough to detect changes in circulating tumor cell levels during treatment, with drops in detected CTC levels matching tumor shrinkage seen on standard CT scans.

"Suddenly, we have a great opportunity to have an impact in cancer in major ways," Toner said.

He said the technology will allow for much more personalized cancer care. "You get a sense of how a patient is responding to treatment."

Eventually, it also may prove useful for cancer screening. And ready access to live cancer cells will advance cancer research.

"We will start to understand the biology of cancer much better," Toner said.

(Editing by Maggie Fox and Xavier Briand)