Listening to Melanoma

University of Missouri-Columbia researchers have found a way to detect the spread of melanoma, a particularly aggressive form of skin cancer, by listening to the sound melanin makes in the blood cells. With as few as 10 cells/sample, oncologists could spot early signs of metastasis before the disease settles in other organs.

This method, photoacoustic detection, combines laser optics and ultrasound by first separating the red blood cells from the plasma, vibrating the blood cells with a laser, and picking up the characteristic signal response of melanoma. The sample is placed in saline solution and exposed to brief bursts of intense blue-laser light. The presence of melanin makes melanoma the only type of of cancer whose cells strongly absorb all wavelengths of light. The abrupt expansion and shrinking of the melanin granules characteristic of melanoma emit cracking sounds that propagate in the saline. The diagnostic procedure could take only 30 min. to determine whether the cancer has begun to travel through the bloodstream, and early discovery could greatly increase the patient's chances for a successful outcome. (