Two systems are used in concert to determine the stage of melanoma.
These were described by Balch et. al., based on outcomes in 60,000 patients1 and published by the American Joint Commission of Cancer (AJCC) and the International Union Against Cancer (UICC) in 2010.² This staging system is used world-wide to classify the patient’s disease and determine prognosis. The major change in the 2010 AJCC/UICC Melanoma Staging System from the previous version, published in 2002, is the inclusion of mitotic activity in the primary as important prognostic factor.
Mitotic activity is histologically defined as mitoses/mm2. A mitotic rate equal to or greater than 1/mm2 denotes a melanoma at higher risk for metastasis.
For patients with localized melanoma (Stage I/II melanoma), the significant prognostic factors were found to be tumor thickness, mitotic rate, ulceration, age, gender, and lesion site. For patients with regional metastasis (Stage III melanoma), the significant factors were the same, with the added factors of tumor burden and number of nodes involved with melanoma.
One part of the staging system involves the TNM Classification. This uses characteristics of the primary tumor (T), the status of the regional lymph nodes (N), and whether or not there are distant metastases and their character (M). Details of the TNM Classification are given on the following page. An example of this system is used is that if a patient had a melanoma between 1.01 to 2 mm in thickness without ulceration, had microscopic involvement in 1 lymph node, and no evidence of distant metastasis, the classification would be T2aN1aM0.
The TNM system is then used to determine the Stage of the melanoma. This is shown following the description of the TNM system in Melanoma Stage below. The Stage ranges from I to IV. Patients with Stage I disease have the best prognosis and those in successive stages have increasingly worse prognosis. Stage I and II represent the primary melanoma without regional or distant metastases. There are subdivisions within Stage I and II depending on the histopathology of the primary (tumor thickness, level, and whether or not ulceration was present. Stage III represents regional metastases and Stage IV represents distant metastases. There are also subdivisions within these Stages depending on the characteristics of the nodal involvement (Stage III) or location of metastases and serum LDH level (Stage IV).