Staging is a way that physicians use to classify a cancer, based on how large (or deep) the cancer has grown, the cancer’s subtype, and whether or where it has spread. Determining which treatments are best for you depends largely on your cancer’s stage.
There are several ways of staging cancers, and the most commonly used one for melanoma is called the TNM system. Your doctor will assign a score that describes your cancer based on the following:
- Tumor depth (T) which reflects the size of the tumor.
- Lymph node status (N) which defines whether the cancer has spread to nearby lymph nodes.
- Metastasis (M) to describe whether the cancer has spread to other body areas distance from the primary site.
Melanomas are classified into the following general stages. There are also subcategories for each stage that your doctor may use for your category.
Stage 0 melanoma
Stage 0 describes a cancer that only involves the top layer of skin. This stage is also called “melanoma in situ.”
Stage 1 melanoma
Melanomas that are classified as stage 1 are no more than 1 millimeter (mm) thick (about the width of sharpened pencil point). The spot or mole’s surface may have broken down.
Stage 2 melanoma
In stage 2 melanomas, the cancer is 1 to 2 mm thick or larger, and the surface might or might not be broken down.
Stage 3 melanoma
Melanomas that are classified as stage 3 are also called regional melanoma and is considered an advanced cancer. Stage 3 melanomas have spread to nearby lymph nodes, lymph vessels or skin. People with stage 3 melanoma may be asked to consider genetic testing.
Stage 4 melanoma
Stage 4 melanomas have spread farther in the body. This means that cancer cells have spread to the lung, liver, brain, bones, or the gastrointestinal tract. People with stage 4 melanoma may be asked to consider genetic testing to help guide treatment decisions and eligibility for a clinical trial.