Zapping bone brings relief from tumor pain. (Cancer).

By unleashing radio waves inside bone, researchers have stopped intractable pain in people with cancer that has spread to their skeletons.

Tumors that form inside bone when cancers spread can be especially painful. The new technique, called radio-frequency ablation, unleashes energy via a needle inserted into bone to reach the edge of the tumor. The radio waves create intense heat that kills nearby tumor cells within about 10 minutes, says study coauthor Matthew R. Callstrom of the Mayo Clinic in Rochester, Minn.

Targeting the surface where the tumor meets the bone seems critical, he says. "Our thought is that nerve fibers in that area-where tumor cells are eroding bone--are the pain generators," he says. Bone itself appears unaffected by the procedure.

The researchers treated 62 patients in whom conventional cancer therapy had failed. Of these, 59 reported significant pain relief, and 28 said they experienced total pain relief at some times, Callstrom says.

"We're not curing cancer with this treatment," he says. "But we're affecting the pain that patients have. The most important [concern] for all these patients is their quality of life."