Shh! Can you hear cancer?
Doctors looking to see if cancer has spread may be able to one day simply listen for it, US researchers report. Researchers at the University of Missouri-Columbia say they have used a technique called photoacoustic detection to pick up the characteristic vibrations of melanoma cells in the blood.
They say their method could let oncologists spot as few as 10 cancer cells in a blood sample, catching a tumour’s spread before it can settle into another organ.
Writing in the October issue of the journal Optics Letters, the researchers say they combined laser techniques from the field of optics and ultrasound techniques from acoustics. They used a laser to make cells vibrate and then picked up the characteristic sound of melanoma cells.
The researchers say they were able to detect melanoma cells obtained from actual patients.
The dark, microscopic granules of melanin in the melanoma cancer cells absorb the energy bursts from the blue laser light. As the melanoma cells expand and contract, they generate crackling sounds that can be picked them up with special microphones and analysed by computer.
Other human cells do not contain pigments with the same colour as melanin, so the melanin signature is easy to tell apart from other noises, says Assistant Professor John Viator, a biomedical engineer who worked on the study. “The only reason there could be melanin in the human blood is that there would be melanoma cells,” he says.
A blood screening test could reassure patients who have a growth removed, or tell a doctor to start chemotherapy quickly because the cancer has already started to spread. “It could take just 30 minutes to find out if there are any circulating cancer cells,” Viator says.