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Staging-TNM Classification

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What is melanoma staging?
Melanoma staging is a classification of the tumor’s size, pathology and extent of spread in the body. It is based on the physician’s physical exam, radiologic tests, blood tests, laboratory test results of the removed tumor and lymph nodes. Staging is necessary for your medical team to determine the appropriate treatment for your level of melanoma.
How is the staging determined?
Melanoma staging is based on primary tumor thickness; spread to lymph nodes; presence of ulceration; metastasis (movement of cancer cells to somewhere else in the system = body); and elevated levels of lactate dehydrogenase (LDH, a blood chemical that is released when cells are damaged). Stages are numerically listed as Stage 0-IV with Stage 0 having the best prognosis and Stage IV having the greatest severity. These stages are based on the TNM classification system.
Melanoma is grouped into Stages 0-IV based on the classifications of tumor size (T), involvement of lymph nodes (N), and distant metastasis (M). The TNM (tumor, node, metastasis) classifications are further subdivided based on the thickness of the Tumor and presence of ulceration, how many and what lymph Nodes are affected, and where the melanoma has Metastasized or spread. The T category is measured in millimeters of actual tumor thickness with T1 = #1mm, T2 = 1.01 – 2mm, T3 = 2.01 – 4mm, T4 = > 4.0 mm. If the melanoma is ulcerated, this increases the severity. Clarks’ level is important in only the T1 category since recent evidence has found thin melanomas that penetrate deeper into the skin’s layers are more virulent. The N category is differentiated by number of regional lymph nodes that have melanoma cells (N1 = l node, N2 = 2-3 nodes, N3 = 4 or more nodes), whether or not the nodes are clinically apparent (noticeable as abnormal on physical exam or x-ray), and the presence of satellite or in-transit metastases (small nests of melanoma cells away from the primary melanoma). The M category is classified as to whether there is distant metastasis or not (M0 = no mets, M1 = yes), and where the metastases are located in the body (M1a = skin, subcutaneous tissues or distant lymph nodes; M1b = lungs; M3 = any other site or distant spread with a high LDH level). For example, a melanoma T2bN0M0, is an ulcerated melanoma with a thickness between 1.01-2mm that has not metastasized to the lymph nodes or a distant part of the body.
(T)umor CategoryTumor ThicknessUlcerationClark’s Level
TXPrimary tumor cannot be accessed (ie, shave biopsy or regressed melanoma)N/AN/A
T0No evidence of primary tumorN/AN/A
TisIn situN/AN/A
T1a#1.0 mmWithoutLevel II or III
T1b#1.0 mmWithLevel IV or V
T2a1.01 – 2.0 mmWithoutN/A
T3a2.01 – 4.0 mmWithoutN/A
T3b2.01 – 4.0 mmWithN/A
T4a> 4.0 mmWithoutN/A
T4b> 4.0 mmWithN/A
Note: The American Joint Committee on Cancer (AJCC) and the World Health Organization (WHO) recommend a sentinel lymph node biopsy for primary tumors >1 mm (any stage other than Tis or T1a).
(N)ode CategoryNumber of Involved NodesClinical Status
NXRegional lymph nodes cannot be accessedN/A
N0No regional lymph node metastasisN/A
N1aMetastasis in 1 nodeClinically non-apparent (microscopic)
N1b1 nodeClinically apparent (macroscopic)
N2a2-3 nodes
N2b2-3 nodesClinically apparent (macroscopic)
N2cN/ASatellite or in-transit metastasis without regional node metastasis
N34 or more or comboMetastasis in $4 regional nodes OR in-transit metastasis or satellite metastasis with regional node metastasis
(M)etastasis CategoryMetastasisSite or Location
MXDistant metastasis cannot be assessedN/A
M0No distant metastasisN/A
M1aYesSkin, subcutaneous tissues, or distant lymph nodes
M1cYesSpread to all other visceral sites OR distant spread at any site combined with an elevated LDH level
Tables adapted from American Joint Committee on Cancer, 2002. In the following section, “Staging – Stages 0-IV,” is an explanation of how the TNM classification is used to determine the stage of melanoma.