Other than visually inspecting the disease, doctors have no genetic blueprint to classify melanomas, a lethal form of skin cancer.
Tumors generally are ranked by how deeply the growth has invaded underlying skin tissue. The deeper it burrows into the skin, the more lethal the cancer, but some patients defy the odds and survive with thick tumors or die from thin ones. “Two melanoma patients with cancers of the same invasion depth and appearance under the microscope can have completely different outcomes,” says Rhoda Alani, M.D., associate professor of oncology, dermatology and molecular biology and genetics at Hopkins' Kimmel Cancer Center.
Alani says the way genes turn their protein-manufacturing machinery on and off in each cancer may help create a signature that can be used to identify tumors that are more prone to kill. These so-called expression patterns can be different from one stage of cancer to the next.
Her research team charted the level of gene expression in melanoma cell lines. Three of the lines mimic the least aggressive type, which grows along the uppermost surface of the skin, called radial growth phase. Four of the cell lines are typical of so-called “vertical growth phase” cancers, which invade inner skin layers, and another three represent the most lethal form -metastatic melanomas.