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.

What does TNM mean?

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.

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).

Tables adapted from American Joint Committee on Cancer, 2002.  www.cancerstaging.net/chapter.pdf

In the following section, "Staging - Stages 0-IV," is an explanation of how the TNM classification is used to determine the stage of melanoma.