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Friday, February 26, 2010

Listening for cancer

Researchers from the University of Missouri have developed a way to detect malignant melanoma cells in lymph nodes.

Melanoma is a deadly and fast growing form of skin cancer. There are different melanoma classification systems that rely on depth of penetration of the tumor and areas affected, but here’s a typical example from The Melanoma Center:

  • Stage 0: the melanoma is in the outer layers of skin
  • Stage I: the melanoma has reached the inner layers of skin but is small
  • Stage II: the melanoma is larger and has spread throughout the skin layers but has not metastasized
  • Stage III: the melanoma has spread to the lymph nodes
  • Stage IV: the melanoma is found throughout the body.

Once a tumor reaches the lymph nodes, entirely different treatment options are needed. Therefore, it’s critical to be able to distinguish Stage II melanomas from Stage III. John Viator and his team are using photoacoustics (laser-induced sound) to do just that.

They injected human melanoma cells into dog and pig lymph nodes and scanned the nodes with their laser. The melanoma cells, containing melanin, react to the scan by absorbing the light. The absorbed light causes the cells to rapidly heat and expand, followed by immediate cooling and contraction. This results in a popping noise that can be detected by special instruments.

Rather than having to examine every cell within a biopsied lymph node, a Herculean task, this technique will allow doctors to determine whether melanoma cells are present, and if so, where.

This procedure has not yet been tried on human patients, but the doctors are hopeful that clinical trials will prove its efficacy.

Here is Dr. Viator explaining the new technique: