Melanoma: Diagnosis - staging melanomas.

Womenshealthmatters.ca - Women’s College Hospital

Home

News

+ Health A-Z

Melanoma Prognosis

Staging is a process of finding out if and by how much a cancer has spread. There are several ways of staging melanomas.

Measuring the size (thickness) of a melanoma under a microscope is believed to be the best way to determine a patient's prognosis (outlook for survival). A micrometer is used by the pathologist to measures the thickness of the melanoma under the microscope. This device is similar to a small ruler. Breslow measurement is the technique used by a pathologist to measure the thickness of a melonoma.

Your physician uses the pathology report to assess the likelihood of future metastases and to design a treatment plan. The thinner the melanoma is, the better the prognosis. In general, melanomas less than one millimetre (mm) in depth have a small chance of spreading. If the melanoma is thicker, the chance of spreading increases. Thickness of the melanoma also dictates what the type of treatment to be used,.

The Clark Level

This is another procedure for assessing a melanoma. Instead of measuring the melonoma, the Clark level describes the melanoma according to the layers of the skin involved. The Clark level of a melanoma uses a scale of I to V. Higher numbers indicate a deeper melanoma.

Clark level I - The cancer involves only the epidermis.

Clark level II - The melanoma has spread somewhat to the upper dermis.

Clark level III - The melanoma involves most of the upper dermis.

Clark level IV - The melanoma has spread to the lower dermis.

Clark level V - The melanoma has spread to the subcutis.

Staging Systems

The most common system used to stage melanoma is the TNM system. This system is similar to the system used with many other cancers. T stands for tumour, its size and how far it has spread within skin and to nearby tissues. N stands for spread to lymph nodes. M is for metastasis or spread to distant organs.

Other staging systems are used by other research groups. Here is an example of another staging system. All of these staging systems help your doctor decide how to best treat your cancer.

Stage 0: The melanoma is in situ, meaning that it involves the epidermis but has not spread to the dermis. This is also called Clark level I.

Stage I: Based on the Breslow measurement, the melanoma is a low-risk tumour (less than 1½ mm or about 1/16 inch in thickness). Using the Clark system, this can be level II or III. It appears to be localized in the skin, and has not been found in lymph nodes or distant organs.

Stage II: The melanoma has a Breslow thickness of greater than 1½ mm (about 1/16 inch), or it can have a Clark level of IV or V. It still appears to be localized to the skin and has not been found in lymph nodes or distant organs.

Stage III: The melanoma has spread to lymph nodes near the affected skin area.

Stage IV: The melanoma has spread beyond the original area of skin and the nearby lymph nodes to other organs such as the lung, liver, or brain, or to distant areas of the skin or lymph nodes.

The five-year relative survival rate for stage I melanoma is over 90 percent. The five-year relative survival rates of stages II and III melanoma are about 80 percent and 50 percent, respectively. About 20 to 30 percent of people with stage IV melanoma survive five years after diagnosis.

Back to Index