Medical Definition of Clark level of invasion
Clark level of invasion: A method for determining the prognosis (outlook) with melanoma. The method was devised by the pathologist Wallace Clark and measures the depth of penetration of a melanoma into the skin according to anatomic layer.
There are five Clark levels of invasion:
Another melanoma measurement system, that of Breslow thickness, named after its originator Alexander Breslow, is in wider use today. In it, invasive tumor thickness is used to predict 5-year survival. For example, a thickness of the melanoma of less than 1.0 millimeters is associated with a 5-year survival of 97% of patients whereas a tumor thickness of more than 8.0 millimeters is associated with 5-year survival of 32%.
Last Editorial Review: 1/25/2017
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