Melanoma stages are assigned based on the size or thickness of the tumor, whether or not it has spread to the lymph nodes or other organs, and certain other characteristics, such as growth rate.
The American Joint Commission on Cancer has developed a uniform staging system that allows doctors to determine how advanced a melanoma is, and to share that information with each other in a meaningful way. This melanoma staging system, known as TNM staging, is composed of three key pieces of information:
T (tumor): Describes the tumor’s thickness, or how deep it has grown into the skin. The thickness of the melanoma, also known as the Breslow measurement, is an important factor in predicting whether or not a tumor has spread. The thicker the melanoma, the greater the chance of it spreading. The rate at which the tumor cells are dividing (also known as the mitotic rate), and the presence or absence of ulceration (an open, bleeding sore) are also considered in determining the T category.
N (node): indicates whether or not the melanoma cancer has spread to nearby lymph nodes, or the channels connecting the lymph nodes.
M (metastasis): refers to whether the melanoma has spread to distant organs, as well as on levels of LDH, a substance in the blood.
Melanoma may be staged before surgery (clinical staging), based on physical exam and imaging results. It will also be staged after surgery (pathologic staging), in which the clinical information will be combined with information gained from biopsies. Because it uses more information, pathologic cancer staging is the most accurate.
The stages of melanoma are:
Stage 0: The cancer cells are confined to the epidermis (the top layer of the skin) and have not spread. At this stage, the cancer is usually handled by surgery alone.
Stage I (stage 1 melanoma): The cancer cells have grown deeper into the skin, but have not spread to the lymph nodes or other parts of the body.
Stage II (stage 2 melanoma): The cancer cells have grown deeper into the skin, or have more high-risk features, but have not spread to the lymph nodes or beyond.
Stage III (stage 3 melanoma): The cancer cells have spread to nearby lymph nodes, but not to distant organs.
Stage IV (stage 4 melanoma): Stage IV melanoma (also known as metastatic melanoma) means the cancer cells have spread beyond the skin and regional lymph nodes to distant organs such as the liver, lungs or brain, or distant lymph nodes and areas of the skin. Your evaluation, as well as your medical history and other relevant factors, will be carefully reviewed by your care team to develop a customized melanoma treatment plan for you.Recurrent melanoma cancer
A relapse of melanoma within 2 centimeters of the original tumor site is considered a local recurrence. Lymph node recurrence and distant recurrence are terms used to describe cancer that has the same DNA characteristics as the original tumor but develops elsewhere in the body, such as the lymph nodes. Lymph node recurrence develops in the lymph node(s) in the area nearest your original melanoma tumor.
It’s considered distant recurrence when melanoma cells enter the bloodstream and develop into tumors at another location in the body. Once they enter the circulatory system, melanoma cancer cells may travel to distant sites in the body. They may develop in any tissue, but they typically grow in the lungs, liver or brain. Metastases may also occur in the bone, heart, pancreas, kidneys or thyroid, among other locations.
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