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RandomFactor writes:

Researchers have developed a way using lasers outside the skin to detect and destroy melanoma cancer cells spreading through the blood. The method is ~1000x more sensitive than current detection methods which require drawing blood.

This approach monitors the entire blood supply of the patient for cancer cells, where current methods examine only a few milliliters which may not contain melanoma cells even if they are circulating.

The new technology, dubbed the Cytophone, uses pulses of laser light on the outside of the skin to heat up cells in the blood. But the laser only heats up melanoma cells — not healthy cells — because these cells carry a dark pigment called melanin, which absorbs the light. The Cytophone then uses an ultrasound technique to detect the teensy, tiny waves emitted by this heating effect.

Researchers have tested the technology on over two dozen light-skinned patients (dark skinned individuals have lower incidence of melanoma) and successfully identified circulating tumor cells 96% of the time with no false positives.

[T]he team also found that after the treatment, the cancer patients had fewer circulating tumor cells. "We used a relatively low energy" with the primary purpose of diagnosing rather than treating the cancer, Zharov said. Yet, even at that low energy, the laser beam seemed able to destroy the cancer cells.

Here's how it works: As the melanin absorbs the heat, the water around the melanin inside the cells begins to evaporate, producing a bubble that expands and collapses, mechanically destroying the cell, Zharov said.

The researchers have also demonstrated the ability in the lab to target breast cancer cells which do not carry melanin by using a marker that binds to those cells.

Most cancer deaths occur due to metastases from the initial tumor to vital organs as a result of circulating tumor cells spreading. Reducing or halting metastasis has significant therapeutic potential.

Journal Reference
In vivo liquid biopsy using Cytophone platform for photoacoustic detection of circulating tumor cells in patients with melanoma

Original Submission