Metastatic melanoma is skin cancer that has spread to other areas of the body such as the brain, lymph nodes, lungs, or bones.

Melanoma is a common type of skin cancer. It starts in the melanocytes, the cells that give skin its color. For this reason, melanoma may develop around a mole or in other pigmented tissues such as those of the eye.

Doctors can often detect melanoma at an early stage. However, some people have metastatic melanoma at the time of diagnosis.

This article explores metastatic melanoma, its causes, and treatment options. It also looks at how people can lower their risk of developing this form of skin cancer.

Melanoma is the third most common skin cancer after basal cell carcinoma and squamous cell carcinoma. It is the fifth most common cancer in males and the sixth most common in females.

Doctors divide melanoma into stages:

  • Stage I: In Stage I melanoma, cancer is localized and there are no signs the cancer has spread to lymph nodes or other sites.
  • Stage II: There are cancer cells in the epidermis and dermis of the skin without evidence the cancer has spread to other sites.
  • Stage III: There are cancer cells in the lymph nodes but there there is no evidence melanoma has metastasized.
  • Stage IV: The cancer has spread to distant areas of the body.

In Stage IV, cancer cells break away from the original tumor site and enter the bloodstream, allowing the melanoma to spread to other parts of the body. Doctors also call this metastatic melanoma.

Although cancer can spread to almost any part of the body, melanoma most commonly metastasizes to other areas of the skin and to subcutaneous tissue, which lies under the skin. Other common metastatic sites include the lungs, liver, bones, and brain.

Melanoma usually starts as a single lesion of abnormal tissue on the skin or mucous membrane.

If doctors do not recognize and treat melanoma early, the lesion can begin to form metastases.

Certain risk factors increase the likelihood that someone will develop melanoma, including:

  • older age
  • previous history of skin cancer
  • family history of melanoma
  • numerous moles, particlularly atypical moles called dysplastic nevi
  • having a pale skin tone that burns easily
  • previous sun damage to the skin
  • high levels of UV exposure to the skin

Certain other risk factors increase the likelihood of melanoma metastasizing. These include having:

  • a melanoma that was incompletely removed
  • advanced primary melanoma
  • aggressive melanoma that grows quickly
  • an unrecognized melanoma

Immunocompromised people may also have a greater risk of metastatic melanoma.

The symptoms of metastatic melanoma depend on where the cancer has spread.

Skin melanoma symptoms include the following:

  • hard lumps and bumps under the skin
  • black marks that appear or change appearance
  • swollen lymph nodes in the neck, armpit, or groin

If melanoma has spread to areas inside the body, a person may have various symptoms, such as:

A doctor may diagnose melanoma after visually examining the skin. They may then recommend the person see a dermatologist.

The dermatologist may take a sample of the abnormal skin called a biopsy. If laboratory analysis confirms melanoma, the dermatologist will remove the lesion entirely.

They may order tests to confirm cancer has not spread. A sentinel node biopsy, for example, can show whether cancer cells have spread to the lymph nodes.

Typically, if a person has no cancer in the lymph nodes, it is unlikely that the melanoma has spread.

If tests find melanoma cells in the lymph nodes, the doctor may use other tests to determine if the melanoma has spread to other areas of the body. These tests may include:

Doctors treat metastatic melanoma according to its spread. If a person has skin melanoma that has not spread, treatment usually involves surgery to remove the tumor and some surrounding tissue.

In some cases, the surgery by itself successfully cures melanoma.

If the melanoma has metastasized, doctors may need to surgically remove tumors and lymph nodes and use other therapies.

Doctors may recommend the following:

  • Immunotherapy: These drugs help a person’s immune system find and kill cancer cells. In people with skin melanoma, intralesional and topical immunotherapy can boost the immune cells around the tumor.
  • Chemotherapy: These powerful agents kill fast-dividing cells, including cancer cells. A doctor may recommend chemotherapy together with immunotherapy.
  • Radiation: This therapy uses high energy rays to kill cancer cells. Doctors may choose this option if the melanoma has spread to the brain or bones.

Doctors can typically cure melanoma if they diagnose and treat it early on. However, metastatic melanoma is more challenging to treat.

The average 5-year survival rate for people with distant metastatic disease is 27.3%.

Although there is no guaranteed way to prevent melanoma, people can lower their risk by limiting their exposure to UV rays.

It is also essential to check the skin regularly to spot new or abnormal growths. Showing these changes to a doctor can help prevent any suspicious areas from developing into cancer.

If a person has a previous medical history of melanoma, they require regular follow-ups and monitoring with their doctor.

Metastatic melanoma is an advanced form of the skin cancer melanoma. It happens when cancer spreads to other areas of the body.

Melanoma develops in the melanocytes, which are melanin-producing cells that give the skin its pigment. This is why melanoma forms around moles and pigmented tissues.

Doctors usually detect melanoma early on, but it may metastasize to other areas of the body if left untreated.

Once melanoma has metastasized, it is more challenging to treat. Treatment may involve a combination of surgery, immunotherapy, chemotherapy, and radiation.

Many people now live for at least 5 years after their initial diagnosis.

People can reduce their risk of developing metastatic melanoma by limiting UV light exposure, practicing sun protection measures, and performing regular skin checks.