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NCI Dictionary of Cancer Terms


Clark levels  listen  (klark LEH-vulz)

  A system for describing how deep skin cancer has spread into the skin. Levels I-V describe the layers of skin involved.

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Clark levels of skin cancer; drawing shows skin with five thin lesions of different depths. In the first lesion (Clark Level I), the cancer is in the epidermis only. In the second lesion (Clark Level II), the cancer has begun to spread into the papillary dermis (upper layer of the dermis). In the third lesion (Clark Level III), the cancer has spread through the papillary dermis into the papillary-reticular dermal interface but not into the reticular dermis (lower layer of the dermis). In the fourth lesion (Clark Level IV), the cancer has spread into the reticular dermis. In the fifth lesion (Clark Level V), the cancer has spread into the subcutaneous tissue.