New Microdevice Captures Rare Cancer Cells

(March 31) -- Cancer patients could soon benefit from a new screening device that can pick out and analyze rare tumor cells from standard blood samples, according to a report today in Science Translational Medicine. The device, which is the size of a business card, could be an alternative to surgery, offering a noninvasive way of monitoring whether tumors are spreading to other parts of the body. All it would require is the prick of a needle.

"The concept is a blood biopsy," explains Massachusetts General Hospital mechanical engineer Shannon Stott, the study's lead author. "The question is, can we just take a simple blood sample and get the same type of information that we would get if we did a surgical biopsy?"

The target cells, known as circulating tumor cells, or CTCs, are most likely shed into the bloodstream by existing tumors. Even if a tumor is removed, these cells can seed a new location, causing the cancer to spread. Not all of them are necessarily harmful, Stott tells AOL News. "But some population of the cells may have the potential to find a new place to take root," she says.

Scientists have long been working to develop a technology that can pick out these cells, but the technical challenges are significant. An FDA-approved technology called CellSearch uses a multistep process to analyze blood for CTCs, but Stott says her device is more sensitive, registering much higher numbers of the fragile cells, and that it could be used to gather more valuable information.

In the new study, Stott and her colleagues used their business-card-sized device to analyze blood samples from 55 prostate cancer patients. The device has nearly 80,000 microposts, or pillars, each of which is coated with an antibody that effectively traps target cancer cells. When the scientists run a volume of blood through it, the CTCs stick to these pillars. The rest of the blood is then washed away, leaving only the target cells for analysis.

Even though these cells can be as rare as one in 10 billion, Stott says the device was able to capture hundreds of them per milliliter of blood. The scientists were also able to study the health of the CTCs -- whether they were ready to die off or poised to divide and spread.

Stott and her colleagues tested samples of each patient's blood taken before prostate-removal surgery, and follow-ups collected after intervals of 24 hours, nine days and three months had elapsed. Many of the patients had little or no CTCs at the start, and with others, their levels dropped immediately after the surgery.

But for one subset, Stott says, the rare cells stuck around through that three-month follow-up. "What we're going to do now is continue to track these patients for the next two years to see if there's any meaning," she says. "Is that a sign of a more invasive prostate cancer?"

Though the current work focuses on prostate cancer, Stott says the technology is applicable to many other forms of the disease -- citing breast cancer and lung cancer as two additional possibilities. She says the group hopes to develop a faster, more efficient plug-and-play version of the device for wider clinical use.