An anonymous reader quotes a report from IEEE Spectrum: 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.
Researchers led by Vladimir Zharov, director of the nanomedicine center at the University of Arkansas for Medical Sciences, 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. The same laser can also be used to destroy the CTCs in real time. Heat from the laser causes vapor bubbles to form on the tumor cells. The bubbles expand and collapse, interacting with the cell and mechanically destroying it.