The first study of a new treatment in humans demonstrates a noninvasive, harmless cancer killer

By Emily Waltz

Tumor cells that spread cancer via the bloodstream face a new foe: a laser beam, shined from outside the skin, that finds and kills these metastatic little demons on the spot.

In a study published today in Science Translational Medicine, researchers revealed that their system accurately detected these cells in 27 out of 28 people with cancer, with a sensitivity that is about 1,000 times better than current technology. That’s an achievement in itself, but the research team was also able to kill a high percentage of the cancer-spreading cells, in real time, as they raced through the veins of the participants.

If developed further, the tool could give doctors a harmless, noninvasive, and thorough way to hunt and destroy such cells before those cells can form new tumors in the body. “This technology has the potential to significantly inhibit metastasis progression,” says Vladimir Zharov, director of the nanomedicine center at the University of Arkansas for Medical Sciences, who led the research.

The spreading of cancer, or metastasis, is the primary cause of cancer-related death. Cancer spreads when cells from primary tumors break off and travel through the bloodstream and lymph system, settling in new areas of the body and forming secondary tumors.

Killing these circulating tumor cells, or CTCs, in the bloodstream before they have a chance to settle could help prevent metastasis and save lives. Simply being able to count CTCs could help doctors more accurately diagnose and treat metastatic cancer—something no device has been able to do efficiently.

Zharov and his team tested their system in people with melanoma, or skin cancer. The laser, beamed at a vein, sends energy to the bloodstream, creating heat. Melanoma CTCs absorb more of this energy than normal cells, causing them to heat up quickly and expand.

This thermal expansion produces sound waves, known as the photoacoustic effect, and can be recorded by a small ultrasound transducer placed over the skin near the laser. The recordings indicate when a CTC is passing in the bloodstream. [READ MORE]