Last year, according to estimates by the National Cancer Institute, close to 69,000 Americans were diagnosed with melanoma, potentially the most aggressive—and deadly—form of skin cancer.
Melanoma begins in pigment-producing cells called melanocytes, the same cells that, when clustered together with surrounding tissue, form moles. Most of us have between 10 and 40 moles on our bodies, harmless growths that tend to fade as we age.
Unfortunately, melanocytes are prone to malignancies, making melanoma one of the most common forms of cancer. When discovered early, the prognosis for patients is excellent. But time is of the essence: If not treated before the cancer spreads to other organs, the consequences can be dire.
Thankfully, determining the presence of melanoma in skin is fairly straightforward. But tests to discover the extent to which the cancer has spread, called staging, are more difficult and time consuming. Thankfully a time-saving, cost-efficient new “photoacoustic” test, a procedure being pioneered by MU’s John Viator, could simplify the process and speed staging.
The photoacoustic method, explains Viator, an assistant professor of biological engineering, involves a form of laser-induced ultrasound. A tabletop device scans a lymph node biopsy with pulses of laser light. Pigment in the melanoma cells absorbs the laser’s energy, causing the cancerous cells to expand and contract as they rapidly heat, then cool.
This action produces a popping noise that sensors can detect. Examining the entire biopsy allows pathologists to identify the area of the node with cancer, thus providing a better idea of where to look for malignant cells.
“This method is quicker and simpler and could be used to improve the efficiency of how doctors determine if the cancer has spread from the original skin lesion into the lymphatic system,” Viator says.
In a study published in the July 2009 edition of the Journal of Biomechanical Engineering, Viator used the photoacoustic method to locate human cancer cells in canine lymph nodes. The next step, he says, is to try the procedure using human lymph nodes.
“It’s very similar to identifying a prize inside a cake,” Viator said. “Instead of looking through the entire cake, we can use our ultrasound to pinpoint a slice or two that might contain the ‘prize.’ In the case of the lymph nodes, when you get a signal, this alerts the pathologist that this is an area of the node that might contain cancer cells. At that point, a pathologist would be able to narrow down the search, saving time and money.”