Stopping cancer's spread is never easy, but when cancer cells metastasize — travel from their original site to invade multiple parts of the body — it is especially difficult. In fact, metastasis is a central reason why cancer is so deadly.

Getting cancer cells to self-destruct rather than multiply would be ideal and that is what an extremely smart new treatment method actually helps make happen. Best of all, lab tests show it catches cells wherever they are in the bloodstream, so metastasis is less of a threat.

When the researchers injected the proteins into a system with flowing blood, the success rate for killing the cancer cells was virtually 100%.

To stop cancer cells in their “tracks,” as they travel through the blood, researchers joined two proteins together: E-selectin, which functioned as an adhesive, and TRAIL (Tumor Necrosis Factor Related Apoptosis-Inducing Ligand), which causes cells to commit cell suicide.

The protein complex is able to "stick" to white blood cells in the blood stream, thereby arming them with this cancer-killing protein complex. And since bumping into white blood cells is virtually unavoidable for cancer cells, as they travel through the blood stream, this was a clever way to administer a good dose of suicide medicine to the metastasizing cells.

“These circulating cancer cells are doomed,” study author Michael King said in a statement. “About 90 percent of cancer deaths are related to metastases, but now we've found a way to dispatch an army of killer white blood cells that cause apoptosis — the cancer cell's own death — obliterating them from the bloodstream.”

When the researchers injected the proteins into a saline solution with cancer cells, the success rate was only about 60%. But when they injected them into a system with flowing blood, the success rate for killing the cancer cells was virtually 100%.

“When surrounded by these guys [white blood cells],” added King, “it becomes nearly impossible for the cancer cell to escape.”

More tests will of course be needed to determine how the treatment works in live animals, and eventually, in humans, and what the appropriate dosing would be. But the method is beautifully simple and logical, so the researchers are very hopeful that it will be similarly effective in people.

The study was carried out by a team at Cornell University and published in Proceedings of the National Academy of Sciences.