New device can spot cancer cells in blood

A highly sensitive microchip may help doctors detect rare traces of cancer circulating in the bloodstream, offering a way to better manage treatment, US researchers said on Wednesday.

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

These circulating tumour cells, or CTCs, are the tiniest fragments of tumours, 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.

Mehmet Toner, whose group developed the device, 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 disease's spread 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 our device from scratch," Toner said.


TRAPPING CANCER CELLS
The device they made uses a business card-sized silicon chip. It has microscopic posts that are coated with antibodies that recognise 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-millilitre 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 tumours – lung, prostate, breast, pancreatic and colorectal.

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

Toner said the technology will allow for much more personalised cancer care. 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," he said.