WASHINGTON, July 16 (Xinhua) -- American researchers have developed a magnetic device that could capture scarce tumor cells in bloodstream, which is a potentially swift and effective tactic for early cancer detection.

A study published Monday in the journal Nature Biomedical Engineering revealed that a wire, after being threaded into a vein, could attract special magnetic nanoparticles engineered to catch hold of tumor cells roaming the bloodstream.

The researchers said cells that had sloughed off the tumor and cruised the bloodstream freely could serve as cancer biomarkers, but they were often scarce, since a blood drew only samples a few milliliters of the total blood volume.

The wire is about the length of a pinky finger and the thickness of a paperclip but it can attract in pig model 10 to 80 times more tumor cells than current blood-based cancer-detection methods, according to the study.

Also, the technique can help doctors evaluate a patient's response to particular cancer treatments, since if the therapy is working, tumor-cell levels in the blood should rise as the cells die and break away from the tumor.

"It could be useful in any other disease in which there are cells or molecules of interest in the blood," said Sam Gambhir, professor of radiology and director of the Canary Center at Stanford University for Cancer Early Detection.

"For example, let's say you're checking for a bacterial infection, circulating tumor DNA or rare cells that are responsible for inflammation in any of these scenarios, the wire and nanoparticles help to enrich the signal, and therefore detect the disease or infection," said Gambhir.

The nanoparticles contain an antibody that latches onto circulating tumor cells, according to the study.

Once the floating tumor cell and nanoparticle are hitched, the cell lugs the tiny magnet around with it, and when the cell-magnet complex flows past the wire, it's compelled by magnetic force to veer from its regular path in the bloodstream and stick to the wire.

Then, the wire is removed from the vein, and the cells are stripped for analysis.

Gambhir and his team tested the device in pigs, placing it in a vein near the pig's ear. That vein is fairly similar to veins in the human arm.

Compared with a different, commercially available wire-based detection method, the wire picked up 500 to 5,000 more tumor cells, according to Gambhir.

"We estimate that it would take about 80 tubes of blood to match what the wire is able to sample in 20 minutes," Gambhir said.