Diagnosis and Staging. What it Means for You.
How is melanoma diagnosed?
To diagnose melanoma, a dermatologist biopsies the suspicious tissue and sends it to a lab, where a dermatopathologist determines whether cancer cells are present.
After the disease is diagnosed and the type of melanoma is identified, the next step is for your medical team to identify the stage of the disease. This may require additional tests including imaging such as PET scans, CT scans, MRIs and blood tests.
The stage of melanoma is determined by several factors, including how much the cancer has grown, whether the disease has spread (metastasized) and other considerations. Melanoma staging is complex, but crucial. Knowing the stage helps doctors decide how to best treat your disease and predict your chances of recovery.
I've been diagnosed with melanoma.
What happens next?
Doctors use the TNM system — developed by the American Joint Committee on Cancer (AJCC) — to begin the staging process. It’s a classification based on three key factors:
T stands for the extent of the original tumor, its thickness or how deep it has grown and whether it has ulcerated.
What Is Breslow depth?
Breslow depth is a measurement (in millimeters) from the surface of the skin to the deepest component of the melanoma.
Tumor thickness: Known as Breslow thickness or Breslow depth, this is a significant factor in predicting how far a melanoma has advanced. In general, a thinner Breslow depth indicates a smaller chance that the tumor has spread and a better outlook for treatment success. The thicker the melanoma measures, the greater its chance of spreading.
Tumor ulceration: Ulceration is a breakdown of the skin on top of the melanoma. Melanomas with ulceration are more serious because they have a greater risk of spreading, so they are staged higher than tumors without ulceration.
N indicates whether or not the cancer has already spread to nearby lymph nodes. The N category also includes “in-transit” tumors that have spread beyond the primary tumor toward the local lymph nodes but have not yet reached the lymph nodes.
M represents spread or metastasis to distant lymph nodes or skin sites and organs such as the lungs or brain.
After TNM categories are identified, the overall stage number is assigned. A lower stage number means less progression of the disease.
What are the melanoma stages, and what do they mean?
Stage 0 and I are localized, meaning they have not spread.
- Stage 0: Melanoma is localized in the outermost layer of skin and has not advanced deeper. This noninvasive stage is also called melanoma in situ.
- Stage I: The cancer is smaller than 1 mm in Breslow depth, and may or may not be ulcerated. It is localized but invasive, meaning that it has penetrated beneath the top layer into the next layer of skin. Invasive tumors considered stage IA are classified as early and thin if they are not ulcerated and measure less than 0.8 mm.
Find out about treatment options for early melanomas.
Intermediate or high-risk melanomas
Localized but larger tumors may have other traits such as ulceration that put them at high risk of spreading.
- Stage II: Intermediate, high-risk melanomas are tumors deeper than 1 mm that may or may not be ulcerated. Although they are not yet known to have advanced beyond the primary tumor, the risk of spreading is high, and physicians may recommend a sentinel lymph node biopsy (SLNB) to verify whether melanoma cells have spread to the local lymph nodes. Thicker melanomas, greater than 4.0 mm, have a very high risk of spreading, and any ulceration can move the disease into a higher subcategory of stage II. Because of that risk, the doctor may recommend more aggressive treatment.
Spread beyond the primary tumor to other parts of the body. There are also subdivisions within these stages.
- Stage III: These tumors have spread to either the local lymph nodes or more than 2 cm away from the primary tumor through a lymph vessel but not yet to the local lymph nodes. Thickness no longer plays a staging role. If local lymph nodes are palpable, meaning they feel enlarged when examined by a doctor, the tumor has reached them, and they are removed. Sometimes melanoma is present even in lymph nodes that are not palpable.
- Sentinel lymph node biopsy (SLNB) is a technique used to determine whether the disease has spread to one or more nearby lymph nodes. Melanomas that have spread to very small areas of nearby skin or underlying tissue but have not reached the lymph nodes are known as “satellite tumors” — and are also included in stage III. The staging system includes metastases so tiny they can be seen only by microscope (micrometastases). The degree of disease advancement depends on whether the tumor has reached the nodes, the number of nodes involved, the number of cancer cells found in them and whether they are microscopic or are palpable and can be seen with the naked eye.
- Stage IV: The cancer has advanced to distant body areas, lymph nodes or organs, most often the lungs, liver, brain, bone and gastrointestinal tract. The two main ways to determine the degree of advancement in stage IV melanoma are the site of the distant tumors and the presence of elevated serum lactate dehydrogenase (LDH) levels. LDH is an enzyme that turns sugar into energy; the more found in blood or body fluids, the more damage has been done.
These stages are each further broken down, from lowest to highest risk, depending on different characteristics of the original tumor and the areas where it has spread.
Cancer staging can be complex and confusing. If you have been diagnosed, ask your doctor to explain your stage in a way you can understand.
What happens after staging?
Allan C. Halpern, MD
Ashfaq A. Marghoob, MD
Ofer Reiter, MD
Last updated: September 2020