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Lasers Detect Skin Cancer More Accurately than Current Techniques
Melanoma is the deadliest form of skin cancer and one of most common types of cancers around. Experts say that while the overall cancer rate has dropped for both men and women in the U.S., melanomas have actually risen by about 5%. The tumors are notoriously difficult to diagnose, but new research shows how a laser probe might be used to diagnose melanoma with a higher accuracy rate than current methods can claim.
Pathologists may frequently disagree about whether or not a tumor is melanoma — a disagreement that potentially affects hundreds of thousands of patients every year. Because of the subjective nature of the process, doctors tend to err on the side of caution, calling more tumors melanoma than actually are, to play it safe. But this high "false positive" rate creates problems in itself, costing the country millions in additional medical bills, not to mention the added stress it puts on the patient.
To address some of these issues, researchers realized that they could use the chemical makeup of the melanoma to differentiate between cancerous and noncancerous lesions. The team designed a technique that uses two laser beams to pump energy into tissue samples. Based on how the cells in the sample respond to the laser, it is possible to determine the ratio of different types of melanin in the sample: a high level of one type, called eumelanin, is a good signal that the sample is cancerous.
The team analyzed 42 tissue samples, 11 of which were cancerous. The new laser technique correctly identified all of them.
The authors estimate that if the new technique is just 50% more accurate than current techniques, it could cut down on 100,000 false-positive per year. The method will need to be tested in a larger variety of tissue samples, and, eventually, on live people who have suspicious skin growths. But the results are encouraging, and based on these early findings, the technique looks like it may offer a more accurate and cost-effective (not to mention less stressful) way to diagnose melanoma.
The research was conducted at Duke University, and published in the February 23, 2011 issue of Science Translational Medicine.
April 22, 2011