Metastatic melanoma

Melanoma is cancer in specific pigmented cells in your body called melanocytes. These cells are found in your skin, mucous membranes and the eye. When a tumor develops from one of these cells, it’s called a melanoma.

This article will cover:

• What is metastatic melanoma?
• Causes and risk factors for metastatic melanomas
• Metastatic melanoma symptoms
• Diagnosis of metastatic melanoma
• Metastatic melanoma stages
• Treatment of metastatic melanoma
• Metastatic stage 3 and 4 melanoma survival rate

What is metastatic melanoma?

Metastatic melanoma is a disease that occurs when the cancerous cells from the original tumor (primary tumor) get loose, spread by traveling through the lymph or blood circulation, and start a new tumor (metastatic tumor) somewhere else. Once it spreads, or metastasizes, the disease is known as metastatic melanoma. This type of melanoma may typically occur during stage 3 or stage 4. Common melanoma metastasis sites include the lymph nodes, lungs, liver, bones and brain.

About 100,640 adults in the United States will be diagnosed with melanoma in 2024, according to the American Cancer Society. Approximately 4 percent of people are diagnosed with melanomas that have spread to distant parts of the body, according to the ASCO. This is the most advanced stage of metastatic melanoma.

The percentage of people diagnosed with melanoma that has spread to nearby lymph nodes is 8.5 percent, according to the National Cancer Institute (NCI). These cases have a slightly better prognosis.

From 2014 to 2018, the incidence rate of melanoma that had spread to distant parts of the body was 0.9 per 100,000 people, according to the NCI.

Melanoma tumors that have metastasized to other parts of the body are still considered melanoma. For example, melanoma found in the lungs is called metastatic melanoma of the lung or melanoma with lung metastases.

Causes and risk factors for metastatic melanomas

Like other skin cancers, melanoma is typically caused by exposure to ultraviolet (UV) rays, which can damage the DNA of cells in the skin, causing them to grow out of control and form cancerous tissue. The sun and tanning beds are the most common sources of damaging UV rays. Metastatic melanoma develops when melanoma cells spread to other areas of the body.

You cannot get metastatic melanoma without first having melanoma, though the primary melanoma may be so small it’s undetectable. Major risk factors for melanomas include:

• Light skin, light-colored hair (blond, red) or light-colored eyes (blue, green)
• Skin prone to burning easily
• Multiple blistering sunburns as a child
• Family history of melanoma
• Frequent exposure to sun or ultraviolet (UV) radiation (from tanning beds, for example)
• Certain genetic mutations
• Exposure to environmental factors, such as radiation or vinyl chloride

Other factors have been connected with increased metastasis. In a 2018 study in the Anais Brasileiros de Dermatologia and a 2019 study in the Journal of the National Cancer Institute, the following factors were associated with higher levels of metastasis:

• Male gender
• Primary tumor thickness of more than 4 mm
• Nodular melanoma, which is a specific subtype that a care team would identify (it typically appears as a raised, hard bump on the skin)
• Ulceration of the primary tumor (broken down skin over the melanoma)

Metastatic melanoma symptoms

Melanoma usually is found in early stages, before it’s become metastatic. If you notice any abnormal moles or discolorations on your skin, don’t hesitate to reach out to your doctor. This is especially important for those with many risk factors. Melanoma is more treatable at early stages, so early identification may prevent metastatic melanoma from developing.

Though a primary tumor is typically found, it’s possible that metastatic melanoma is detected elsewhere in the body and causes symptoms without any signs of a primary tumor.

Metastatic melanoma symptoms and signs may include:

• Fatigue
• Swollen or painful lymph nodes
• Weight loss
• Loss of appetite
• Trouble breathing or a cough that doesn’t go away
• Bone pain
• Headaches
• Seizures
• Swelling of the liver

Symptoms vary depending on where the metastasis spreads in the body.

If melanoma spreads to the lungs, specific symptoms may include:

• Coughing, with or without blood
• Chest pain
• Shortness of breath
• Fluid around the lungs

If melanoma spreads to the brain, specific symptoms may include:

• Headache
• Paralysis in the arms or legs
• Sleepiness
• Problems with remembering things
• Changes in emotions or behavior
• Difficulties hearing, seeing or swallowing
• Seizures
• Nausea or vomiting

If melanoma spreads to the bones, specific symptoms may include:

• Bone aches and pains
• Back pain or numbness
• Easily fractured bones
• Changes in calcium levels, from bones being broken down, which may cause sleepiness, confusion or changes in bowel habits

If melanoma spreads to the liver, specific symptoms may include:

• Loss of appetite
• Fatigue or lethargy
• Jaundice (yellowing of the skin or whites of eyes)
• Swelling in the abdomen or legs
• Itchiness

Diagnosis of metastatic melanoma

Your care team may use several tests to diagnose metastatic melanoma.

If there’s evidence of a primary tumor, a biopsy may be taken. For this, a small section of suspected cancerous skin is removed with a razor, scalpel or small punch tool. The removed tissue is examined under a microscope to determine whether it’s melanoma.

Additional tests are needed to determine whether the cancer is metastatic melanoma, or if there’s no visible primary tumor. To test for metastatic melanoma, or melanoma that has spread to lymph nodes or distant parts of the body, your care team may perform the following tests.

• Lymph node mapping and sentinel lymph node biopsy (SLNB): Your doctor may perform a physical exam of your lymph nodes and check for swelling or physical masses. If no tumors are found (because they may just be too small to see or feel), an SLNB may be done. For an SLNB, a radioactive dye is injected to locate the primary tumor. Then, the doctor will remove the lymph nodes that the dye traveled to and check them for melanoma.
• Computed tomography (CT) scan, positron emission tomography (PET) scan, magnetic resonance imaging (MRI) scan or ultrasound exam: Each of these scans is a noninvasive way to look inside your body and check for tumors.
• Blood chemistry studies: Cancer may cause elevated or abnormal levels of certain substances in your blood. A laboratory test can identify if your blood chemistry shows signs of a cancerous tumor.

Metastatic melanoma stages

Your melanoma is given a stage depending on how much the cancer has progressed upon diagnosis. Melanoma staging uses the TNM system, which classifies a melanoma’s stage based on three main factors.

• T is for tumor, and takes into consideration a tumor’s thickness and whether the skin is decaying around the tumor.
• N is for nodes, and considers whether the cancer has spread to nearby lymph nodes.
• M is for metastasis, or whether the cancer has spread or not.
• Stages are labeled from 0 to 4.

Stages 0, 1 and 2 are melanoma. Stage 3 (some cases) and stage 4 melanomas are considered metastatic melanomas.

Metastatic stage 3 melanoma

Stage 3 is broken down into several subcategories.

• Stage 3A
  • These tumors are no more than 2 mm thick, and small tumors have spread to one to three nearby lymph nodes. The primary tumor may be ulcerated.
• Stage 3B includes two presentations:
  • There’s no sign of a primary tumor, but cancer has spread to one nearby lymph node, or to small areas of nearby skin and close lymph channels.
  • The cancer is no more than 4 mm thick and has spread to one to three lymph nodes or small areas of nearby skin. The primary tumor may be ulcerated.
• Stage 3C includes four possible presentations:
  • There’s no sign of a primary tumor. Cancer has spread to two or more nearby lymph nodes (with at least one being so big it can be seen without a microscope), or it’s spread to small areas of skin and reached nearby lymph nodes, or it’s spread to nearby clumped lymph nodes.
  • The primary tumor is no more than 4 mm thick. It’s either spread to more than four lymph nodes or to clumped lymph nodes, or it’s spread to small nearby areas of skin and into nearby lymph nodes.
  • The primary tumor is 2 to 4 mm and ulcerated, or more than 4 mm and not ulcerated. It’s spread to one or more nearby lymph nodes or has spread to small areas of nearby skin and lymph channels.
  • The primary tumor is more than 4 mm thick and is ulcerated. It’s spread to one to three nearby lymph nodes, or has spread to small areas of nearby skin and lymph channels.
• Stage 3D
  • The tumor is thicker than 4 mm and is ulcerated. It’s either spread to small areas of the skin and at least two nearby lymph nodes, to lymph nodes that are clustered together, or to four or more nearby lymph nodes.

Metastatic stage 4 melanoma

Once a melanoma has spread to distant parts of the body, such as the lungs, liver or other areas of skin, it’s considered stage 4. This cancer can be any thickness and may or may not have spread to nearby lymph nodes.

Stage 4 can be further staged based on where the cancer has spread:

• M1a: Cancer has metastasized to skin that’s far from the original site and/or to areas with soft tissue.
• M1b: Cancer has extended to the lungs.
• M1c: Cancer has spread to a location other than your central nervous system (CNS).
• M1d: There is cancer spread to your CNS. This includes your brain, spinal cord and/or cerebrospinal fluid.

Treatment of metastatic melanoma

Metastatic melanomas can be difficult to treat. The five-year survival rate for people diagnosed with melanoma that has spread to nearby lymph nodes is 66 percent, according to the American Cancer Society. When cancer has spread to distant parts of the body, there may also be other metastases too small to detect by scans. For people diagnosed with stage 4 melanoma, or melanoma that has spread to distant parts of the body, the five-year survival rate is 27 percent.

For stage 3 and 4 melanomas, the following treatments may be used:

• Surgery removes the tumor with scalpels or other instruments. Local numbing is typically used to allow for complete removal of the primary tumor. Usually, surgery also removes all lymph nodes near the site of the primary tumor, though this may carry some risks. You and your care team can decide whether lymph node dissection is right for you. Surgery may also be used to remove metastatic tumors (for example, in the brain or lungs), which may extend life span and help control symptoms of cancer. If surgery isn’t possible, other options may be used to shrink the size of metastatic melanomas.
• Targeted therapies are drugs that kill cells with specific mutations. Some melanomas have particular mutations that make them good candidates for these drugs, and these targeted therapies can destroy the tumor and its metastases selectively.
• Immunotherapy medications, such as PD-1 inhibitors, train your immune system to recognize and attack cancer cells. They may be more successful in shrinking metastatic melanomas.
• Radiation therapy uses high-energy beams to kill cancer cells. Radiation may be used after surgery to prevent recurrence of cancer. It also may help manage symptoms of metastases, such as bone aches and pains. Chemotherapy is a cancer treatment that uses various drugs to kill the tumor.
• Chemotherapy isn’t as likely to be used as treatment due to the increasing success rates of targeted therapy and immunotherapy drugs.
• Clinical trials are studies researching new therapies. New drugs are always being developed and tested, and some may be able to treat your cancer.

Multiple therapies can be used at any given time, and your care plan is a dynamic process. You and your care team should discuss all the options and decide on a treatment plan. Each treatment has different side effects, and it’s important to feel fully informed of all the associated risks. Other medications and options may help manage the symptoms of your cancer treatment, so you can live the highest quality of life possible throughout the course of your treatment and disease.

Metastatic stage 3 and 4 melanoma survival rate

When doctors talk about cancer survival, they typically speak of the five-year survival rate—or how many cancer patients are estimated to be alive five years after being diagnosed or starting treatment. These are estimates based on groups of previous patients and older treatments. Statistics may give you and your care team information, but keep in mind that everyone’s response to treatment is different.

According to the American Cancer Society, the five-year survival rate for people diagnosed with stage 3 melanoma that has spread to nearby lymph nodes or structures (regional spread) is 66 percent. For patients diagnosed with stage 4 melanoma (distant spread), the five-year survival rate is 27 percent.

Another measure that helps estimate the outcome of cancer is the prognosis, meaning your chances of recovery or recurrence. People with stage 3 melanoma have an intermediate to high risk for recurrence. Stage 4 melanoma has a high likelihood of recurring and is considered difficult to treat.

Treatments for melanoma are improving every day, and the most current treatments are more targeted, which also means fewer side effects. As a result, a patient’s prognosis and survival rates for advanced-stage melanomas are expected to improve as well.