Detecting melanoma with laser-based technique

Compiled by BioPhotonics staff

High-resolution images from a new laser-based tool could help doctors better diagnose melanoma, the deadliest form of skin cancer.

The tool, developed by researchers at Duke University, probes skin cells using two lasers to pump small amounts of energy – less than that of a laser pointer – into a suspicious mole. Scientists then can analyze the way the energy redistributes in the skin cells to pinpoint microscopic locations of different skin pigments. It’s the first time that scientists have been able to identify chemical differences between cancerous and healthy skin tissue.

The team imaged 42 skin slices with the laser tool and found that melanomas tend to have more eumelanin – a kind of skin pigment – than healthy tissue does. They used the amount of eumelanin as a diagnostic criterion to correctly identify all 11 melanoma samples in the study. Results of their findings appeared in the Feb. 23, 2011, issue of Science Translational Medicine (doi: 10.1126/scitranslmed.3001604).

The new method will be further tested using thousands of archived skin slices to verify whether it can identify changes in moles that eventually did become cancerous. It could prevent more than 100,000 false melanoma diagnoses, even if it is only 50 percent more accurate than biopsies.

Previously, doctors used a light and a magnifying glass or tissue biopsy to remove suspicious skin cells. They would inspect the cells under a microscope to detect signs of the disease. In 14 percent of biopsy diagnoses, pathologists were uncertain whether the sample cells were cancerous. They followed the “when in doubt, cut it out” philosophy and, if they were not sure about the health of the tissues around the diseased cells, they would remove those as well, costing thousands of dollars.

Seeing such a great need for a more accurate way to diagnose melanoma, the researchers set out to develop the new imaging tool. It now is commercially available and would need only to be added to the microscopes that pathologists already use to diagnose melanomas. Suspicious moles still would have to be removed from a patient and then imaged to detect cancer, the scientists say.

The researchers are working on imaging skin cancers grafted onto mice to see whether the tool could become a device for dermatologists to scan a mole without removing it.