From Mole to Metastatic: The Different Stages of Melanoma
Catching melanoma early can truly be life-saving.
If you are diagnosed with melanoma—a rare but serious type of skin cancer—your doctor will also need to determine the stage of melanoma. The exact stage of melanoma will be important in choosing the appropriate treatment for the skin cancer.
Stages of melanoma, like with other types of cancer, refer to how the cancer is progressing and spreading (or “metastasizing”) throughout the body. The higher the stage, the more serious the melanoma is and the harder it is to treat and prevent melanoma recurrence.
Factors That Determine Staging
“When we look at the staging of melanoma, we’re interested in three things: TNM, [or] tumor, node, metastasis,” says Kaveh Alizadeh, MD, plastic and reconstructive surgeon in New York City. “Depending on a combination of these, you can end up in different stages.”
Doctors will look at the thickness and appearance of the tumor. If the tumor is only affecting the dermis or epidermis (the top two layers of the skin), these will be a lower stage of melanoma. Tumors are categorized by a “T stage,” using the following scale:
T1 is less than or equal to 1.0 mm.
T2 is between 1.0 and 2.0 mm.
T3 is between 2.1 and 4.0 mm.
T4 is greater than 4.0 mm.
Nodes, meaning the lymph nodes, are the first thing to be affected whenever a cancer spreads. Lymph nodes are located throughout the body and are part of the immune system.
First, this may be “micro-metastasis,” which is when “the node itself doesn’t look enlarged but there’s tiny infiltration of [cancer] cells into that node,” says Dr. Alizadeh. When lymph nodes are fully affected, they become swollen and help spread melanoma throughout the body.
Doctors categorize nodal involvement with the “N stage,” using the following scale:
N0 means no nodes are affected by melanoma.
N1 means one nearby node is affected.
N2 means two or three nodes are affected.
N3 means more than four nodes are affected.
Metastasis can also occur at different degrees of severity. Doctors will determine if the metastasis or regional (affecting only nearby lymph nodes and organs) or distant (reaching nodes and organs that are far from the tumor). Metastasis is categorized by the “M stage,” using the following scale:
M0 means no metastasis has occurred.
M1a means metastasis to skin layers or distant lymph nodes.
M1b means metastasis to lung.
M1c means any other distant form of metastasis.
Because higher stages come with a higher risk of melanoma recurrence, catching melanoma early can truly be life-saving. Those who are treated in the early stages tend to have a better chance of survival and enjoy a longer life. For example, the 10-year survival rate for someone treated in stage 1 melanoma is more than 90 percent, according to the American Cancer Society.
“The good news for people that have later stage melanomas is that they have more potential for disease-free survival, and more potential with some of these newer treatments that are out there to fight the tumors for them,” says Dr. Alizadeh.
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When we look at the staging of melanoma,
we're interested in three things.
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TNM, for tumor, node, metastasis.
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And depending on the combination of these,
you can end up in a different stage.
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Why is that important when your doctor
tells you you're a stage one, stage two,
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stage three, or stage four?
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That's important because
the survival can become different,
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depending on which stage you're at.
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The decision making becomes different,
depending on where you're at.
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And the potential trials that may be
open to you will become different.
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The early stages are the ones that,
the tumor's microscopic.
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Once you get past the membrane that
connects the skin to the underlying
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structure, at that level, the tumor
now has a potential of spreading,
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because now it can sort of go in and start
infiltrating the underlying structures and
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potentially blood vessels and
nodes and so forth.
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So that's when we become
interested in the nodes.
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The nodes,
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we either look at them as there's no
nodal involvement, which is good.
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That means it's an earlier stage.
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Or they could be micro-metastasis, where
the node itself doesn't look enlarged, but
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there's tiny infiltration
of cells into that node.
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And then, last but not least,
we're interested in the metastasis.
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Is metastasis regional, or has it,
in fact, gone to distant locations?
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For example,
if you have a metastasis in your brain,
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that unfortunately is the behavior of
a rapidly dividing, aggressive cancer.
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And so, the management becomes different.
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And once you pool all of this information
together, now you have the T Staging,
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which is for the tumor.
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Whether it's less than a millimeter or
one to two millimeters, or
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greater than four millimeters.
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Each of these will put
you in a different stage.
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And then, the N for nodes.
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Whether it's no nodes,
two to three nodes, nodes in transit, or
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multiple nodes that are distant.
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That could put you in
a different category.
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And M for metastasis,
which is whether you have no metastasis,
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thankfully, early stage,
a regional metastasis versus
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distant metastasis on the number
of areas where it's metastasized.
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The good news for people that have later
stage melanoma is that they have more
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potential for disease-free survival, and
more potential with some of these newer
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treatments that are out there
to fight the tumors for them.
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Melanoma skin cancer stages. Atlanta, GA: American Cancer Society, 2017. (Accessed on March 15, 2019 at https://www.cancer.org/cancer/melanoma-skin-cancer/detection-diagnosis-staging/melanoma-skin-cancer-stages.html.)
Treatment of melanoma skin cancer, by stage. Atlanta, GA: American Cancer Society, 2018. (Accessed on March 15, 2019 at https://www.cancer.org/cancer/melanoma-skin-cancer/treating/by-stage.html.)
What are basal and squamous cell skin cancers. Atlanta, GA: American Cancer Society, 2016. (Accessed on March 15, 2019 at https://www.cancer.org/cancer/basal-and-squamous-cell-skin-cancer/about/what-is-basal-and-squamous-cell.html.)