Now, a new laser-based tool to detect skin cancer

Scientists developed laser-based tool which could help doctors better diagnose melanoma.

Updated: Feb 24, 2011, 13:18 PM IST

Washington: Scientists have developed a new laser-based tool which they claim could help doctors better diagnose melanoma, the deadliest form of skin cancer
that kills thousands of people every year.

Developed by a team at the Duke University in the US, the tool produces high-resolution images by pumping small amounts of energy into skin cells and help pinpoint rogue
cells.

Thomas Matthews, who helped develop the new two-laser microscopy technique at Duke, said the new tool enabled scientists for the first time to identify substantial chemical differences between cancerous and healthy skin tissues.

For the study, appeared in journal Science Translational Medicine, the Duke team imaged 42 skin slices with the new tool and the images showed that melanomas tend to
have more eumelanin, a kind of skin pigment, than healthy tissue.

Using the amount of eumelanin as a diagnostic criterion, the team used the tool to correctly identify all 11melanoma samples in the study.

The technique will be further tested using thousands of archived skin slices. Studying old samples will verify whether the new technique can identify changes in moles that
eventually did become cancerous.

Even if the technique proves, on a large scale, to be 50 per cent more accurate than a biopsy, it would prevent about 100,000 false melanoma diagnoses, said Warren S Warren, of Duke`s Centre for Molecular and Biomolecular Imaging, who
oversaw the development of the new melanoma diagnostic tool.

Melanoma is the fifth-most common cancer for males and sixth-most common for females. In 2010, US doctors diagnosed nearly 115,000 new cases of the disease, with nearly 8,700 resulting in death. The cancer is also one of the few where
the death rate is increasing.

Doctors typically use a light and a magnifying glass or tissue biopsy, where a pathologist removes suspicious skin cells and looks at them under a microscope, to spot signs of
disease.

But using a lens and a light is a "17th century" method that is only 85 per cent accurate, at best, and tissue biopsy is not much more reliable, Warren said.

In 14 per cent of biopsy diagnoses, pathologists would disagree on whether or not the sampled cells were cancerous.

The statistic implies that two pathologists would have opposing diagnoses on 214,000 to 643,000 melanoma cases each year, Warren said.

When studying biopsied tissue, doctors typically follow the "when in doubt, cut it out" philosophy. The first and second tissue biopsies can cost thousands of dollars.

If the melanoma is thought have spread, patients may then have lymph nodes in their arms removed or undergo chemotherapy, which dramatically adds to treatment costs.
But not all of the extra treatment is needed because not all of the biopsied tissues are actually cancerous.

Doctors need a more accurate way to diagnose melanoma, Warren said.

PTI