Using Laser Technology to Detect Cancer Cells

By Joshua Mansour, MD

We’ve come a long way since hearing Dr. Evil of Austin Powers movie fame describe “a sophisticated heat beam, which we call ‘a laser’” to take over the world, or sitting in awe watching Jedi knights in Star Wars blast through enemies using lightsabers. Now in real life, scientists are exploring different ways the laser can detect cancer cells and save lives.

Cancer tumors have the ability to break off from their primary site and spread from their primary organ to other sites of the body via the bloodstream and lymphatic system.  The spreading of cancer, known as “metastasis,” is the leading cause of cancer-related death.  Although there are currently blood tests designed to detect cancer cells in the blood, known as circulating tumor cells, many times they cannot pick up minimal cancer cells released early on.  If these current tests return as positive, this frequently means that there is a high level of cancerous cells in the blood that have spread to other organs.

However, the diagnosis and treatment of these cancer cells in the blood may soon change.  A recent study published in Science Translation Medicine showed that researchers have devised a laser that can detect these malignant cells and zap them from outside of the body.  The current standard methods of detection have limited sensitivity for picking up minimal cells at early stages of the disease, therefore possibly missing an opportunity to eliminate them at a treatable point in the illness.   A team led by biomedical engineer Vladimir Zharov, director of nanomedicine at the University of Arkansas for Medical Sciences, has developed a method in hopes of changing that modality.

Researchers have devised a laser that can detect malignant cells and “zap” them from outside the body.

In studies with melanoma, they have coupled a laser with an ultrasound detector to create a ‘Cytophone,’ a device that identifies cells acoustically.  To break it down, a laser is first shined on the surface of a person’s skin, penetrating right into some of the near-surface blood vessels.  The passing melanoma cells will then ‘heat up’ because of their darker pigment and create a small ‘acoustic wave’ that then gets picked up by the ultrasound detector.   Melanoma cells absorb more of the energy from the laser because of their dark pigment, allowing them to heat up quickly and expand.

This method can pick up a single circulating tumor cell per liter of blood, which makes this up to approximately 1,000 times more sensitive than other available methods of detection that typically examine only about 7- 8 milliliters of a sample of blood.  Additionally, the cytophone was able to detect small clots of blood.

Researchers have tested this on 28 patients with melanoma and 19 healthy volunteers.  Researchers were able to discover that within as little as 10 seconds and as long as 1 hour, the cytophone was able to detect circulating tumor cells in 27 of the 28 patients.  It also did not return any false positives on the healthy volunteers.  Moreover, it was found that when the energy level of the laser was turned up (still to a safe intensity) that the amount of circulating tumor cells came down over the hour, without causing any side effects.

They have tested this on 28 patients with melanoma and 19 healthy volunteers.  Researchers found that within as little as 10 seconds and as long as 1 hour, the cytophone was able to detect circulating tumor cells in 27 of the 28 patients.  It also did not return any false positives on the healthy volunteers.  Moreover, it was found that when the energy level of the laser was turned up (still to a safe intensity) that the amount of circulating tumor cells came down over the hour, without causing any side effects.

Even though this has been tested recently in melanoma, and the dark pigment of melanin plays a role in its detection, Zharov and his colleagues are currently working to develop methods of “tagging” other cancer cells with small nanoparticles to be able to ‘heat up’ and be distinguished from the normal cells.

Movies aside, the future holds promise in the new hope of using lasers to fight off the evil invasions of metastasis.