Once the type of melanoma has been established, the next step is to classify the disease as to its degree of severity.
Classifications for melanomas are called stages. The stage refers to the thickness, depth of penetration, and the degree to which the melanoma has spread. The staging is used to determine treatment.
Early melanomas (Stages 0 and I) are localized; Stage 0 tumors are in situ, meaning they are noninvasive and have not penetrated below the outer layer of the skin (the epidermis). Stage I tumors have invaded below the epidermis into the skin’s next layer (the dermis), but are small and have no other traits such as ulceration that put them at high risk of spreading (metastasizing) to nearby lymph nodes or beyond.
Stage II tumors, though localized, are larger (generally over 1 mm. thick) and/or may have other traits such as ulceration that put them at high risk of spreading to the nearby lymph nodes or beyond. They are considered intermediate or “high-risk” melanomas. More advanced melanomas (Stages III and IV) have metastasized to other parts of the body. There are also subdivisions within stages.
Guide to StagingNew Melanoma Staging System – By means of an unprecedented cooperative effort among cancer centers around the world, the classification system recommended by the American Joint Commission on Cancer (AJCC) was updated in 2010. New findings about melanoma were incorporated to provide the most accurate diagnosis and prognosis (a forecast of how the disease is likely to progress).
Lymph Node InvolvementOnce a melanoma has progressed beyond Stage II, it has spread beyond the original site. It is most likely to have reached the lymph nodes that are closest to the tumor.