Detection of circulating melanoma cells in human blood using photoacoustic flowmetry

Detection of circulating tumor cells (CTC´s) in human blood and lymph systems has the potential to aid clinical decision making in the treatment of cancer. The presence of CTC´s may signify the onset of metastasis, indicate relapse, or may be used to monitor disease progression. A photoacoustic flowmetry system was designed and tested for detecting circulating melanoma cells (CMC´s) by exploiting the broadband absorption spectrum of melanin within CMC´s. The device was tested on cultured melanoma cells in saline suspension and in a Stage IV melanoma patient. The device showed a detection threshold of a single melanotic melanoma cell from culture. Transient photoacoustic events were detected in a sample derived from a Stage IV melanoma patient that corresponded to particles passing through the laser beam path, indicating the presence of single melanoma cells in the human circulatory system.