Stages of Melanoma

After melanoma has been diagnosed, tests may be done to find out if cancer cells have spread within the skin or to other parts of the body.

The process used to find out whether cancer has spread within the skin or to other parts of the body is called staging. The information gathered from the staging process determines the stage of the disease. It is important to know the stage in order to plan treatment.

For melanoma that is not likely to spread to other parts of the body or recur, more tests may not be needed. For melanoma that is likely to spread to other parts of the body or recur, the following tests and procedures may be done after surgery to remove the melanoma:

• Lymph node mapping and sentinel lymph node biopsy: The removal of the sentinel lymph node during surgery. The sentinel lymph node is the first lymph node in a group of lymph nodes to receive lymphatic drainage from the primary tumor. It is the first lymph node the cancer is likely to spread to from the primary tumor. A radioactive substance and/or blue dye is injected near the tumor. The substance or dye flows through the lymph ducts to the lymph nodes. The first lymph node to receive the substance or dye is removed. A pathologist views the tissue under a microscope to look for cancer cells. If cancer cells are not found, it may not be necessary to remove more lymph nodes. Sometimes, a sentinel lymph node is found in more than one group of nodes.
• CT scan (CAT scan): A procedure that makes a series of detailed pictures of areas inside the body taken from different angles. The pictures are made by a computer linked to an x-ray machine. A dye may be injected into a vein or swallowed to help the organs or tissues show up more clearly. This procedure is also called computed tomography, computerized tomography, or computerized axial tomography. For melanoma, pictures may be taken of the neck, chest, abdomen, and pelvis.
• PET scan (positron emission tomography scan): A procedure to find malignant tumor cells in the body. A small amount of radioactive glucose (sugar) is injected into a vein. The PET scanner rotates around the body and makes a picture of where glucose is being used in the body. Malignant tumor cells show up brighter in the picture because they are more active and take up more glucose than normal cells do.
• MRI (magnetic resonance imaging) with gadolinium: A procedure that uses a magnet, radio waves, and a computer to make a series of detailed pictures of areas inside the body, such as the brain. A substance called gadolinium is injected into a vein. The gadolinium collects around the cancer cells so they show up brighter in the picture. This procedure is also called nuclear magnetic resonance imaging (NMRI).
• Ultrasound exam: A procedure in which high-energy sound waves (ultrasound) are bounced off internal tissues, such as lymph nodes, or organs and make echoes. The echoes form a picture of body tissues called a sonogram. The picture can be printed to be looked at later.
• Blood chemistry studies: A procedure in which a blood sample is checked to measure the amounts of certain substances released into the blood by organs and tissues in the body. For melanoma, the blood is checked for an enzyme called lactate dehydrogenase (LDH). High LDH levels may predict a poor response to treatment in patients with metastatic disease.

The results of these tests are viewed together with the results of the tumor biopsy to find out the stage of the melanoma.

There are three ways that cancer spreads in the body.

Cancer can spread through tissue, the lymph system, and the blood:

• Tissue. The cancer spreads from where it began by growing into nearby areas.
• Lymph system. The cancer spreads from where it began by getting into the lymph system. The cancer travels through the lymph vessels to other parts of the body.
• Blood. The cancer spreads from where it began by getting into the blood. The cancer travels through the blood vessels to other parts of the body.

Cancer may spread from where it began to other parts of the body.

When cancer spreads to another part of the body, it is called metastasis. Cancer cells break away from where they began (the primary tumor) and travel through the lymph system or blood.

• Lymph system. The cancer gets into the lymph system, travels through the lymph vessels, and forms a tumor (metastatic tumor) in another part of the body.
• Blood. The cancer gets into the blood, travels through the blood vessels, and forms a tumor (metastatic tumor) in another part of the body.

The metastatic tumor is the same type of cancer as the primary tumor. For example, if melanoma spreads to the lung, the cancer cells in the lung are actually melanoma cells. The disease is metastatic melanoma, not lung cancer.

The stage of melanoma depends on the thickness of the tumor, whether cancer has spread to lymph nodes or other parts of the body, and other factors.

To find out the stage of melanoma, the tumor is completely removed and nearby lymph nodes are checked for signs of cancer. The stage of the cancer is used to determine which treatment is best. Check with your doctor to find out which stage of cancer you have.

The stage of melanoma depends on the following:

• The thickness of the tumor. The thickness of the tumor is measured from the surface of the skin to the deepest part of the tumor.
• Whether the tumor is ulcerated (has broken through the skin).
• Whether cancer is found in lymph nodes by a physical exam, imaging tests, or a sentinel lymph node biopsy.
• Whether the lymph nodes are matted (joined together).
• Whether there are:
  • Satellite tumors: Small groups of tumor cells that have spread within 2 centimeters of the primary tumor.
  • Microsatellite tumors: Small groups of tumor cells that have spread to an area right beside or below the primary tumor.
  • In-transit metastases: Tumors that have spread to lymph vessels in the skin more than 2 centimeters away from the primary tumor, but not to the lymph nodes.
  
• Whether the cancer has spread to other parts of the body, such as the lung, liver, brain, soft tissue (including muscle), gastrointestinal tract, and/or distant lymph nodes. Cancer may have spread to places in the skin far away from where it first formed.

The following stages are used for melanoma:

Stage 0 (Melanoma in Situ)

In stage 0, abnormal melanocytes are found in the epidermis. These abnormal melanocytes may become cancer and spread into nearby normal tissue. Stage 0 is also called melanoma in situ.

Stage I

In stage I, cancer has formed. Stage I is divided into stages IA and IB.

• Stage IA: The tumor is not more than 1 millimeter thick, with or without ulceration.
• Stage IB: The tumor is more than 1 but not more than 2 millimeters thick, without ulceration.

Stage II

Stage II is divided into stages IIA, IIB, and IIC.

• Stage IIA: The tumor is either:
  • more than 1 but not more than 2 millimeters thick, with ulceration; or
  • more than 2 but not more than 4 millimeters thick, without ulceration.
• Stage IIB: The tumor is either:
  • more than 2 but not more than 4 millimeters thick, with ulceration; or
  • more than 4 millimeters thick, without ulceration.
• Stage IIC: The tumor is more than 4 millimeters thick, with ulceration.

Stage III

Stage III is divided into stages IIIA, IIIB, IIIC, and IIID.

• Stage IIIA: The tumor is not more than 1 millimeter thick, with ulceration, or not more than 2 millimeters thick, without ulceration. Cancer is found in 1 to 3 lymph nodes by sentinel lymph node biopsy.
• Stage IIIB:

  (1) It is not known where the cancer began or the primary tumor can no longer be seen, and one of the following is true:

  • cancer is found in 1 lymph node by physical exam or imaging tests; or
  • there are microsatellite tumors, satellite tumors, and/or in-transit metastases on or under the skin.

    or

  (2) The tumor is not more than 1 millimeter thick, with ulceration, or not more than 2 millimeters thick, without ulceration, and one of the following is true:

  • cancer is found in 1 to 3 lymph nodes by physical exam or imaging tests; or
  • there are microsatellite tumors, satellite tumors, and/or in-transit metastases on or under the skin.

    or

  (3) The tumor is more than 1 but not more than 2 millimeters thick, with ulceration, or more than 2 but not more than 4 millimeters thick, without ulceration, and one of the following is true:

  • cancer is found in 1 to 3 lymph nodes; or
  • there are microsatellite tumors, satellite tumors, and/or in-transit metastases on or under the skin.

• Stage IIIC:

  (1) It is not known where the cancer began, or the primary tumor can no longer be seen. Cancer is found:

  • in 2 or 3 lymph nodes; or
  • in 1 lymph node and there are microsatellite tumors, satellite tumors, and/or in-transit metastases on or under the skin; or
  • in 4 or more lymph nodes, or in any number of lymph nodes that are matted together; or
  • in 2 or more lymph nodes and/or in any number of lymph nodes that are matted together. There are microsatellite tumors, satellite tumors, and/or in-transit metastases on or under the skin.

    or

  (2) The tumor is not more than 2 millimeters thick, with or without ulceration, or not more than 4 millimeters thick, without ulceration. Cancer is found:

  • in 1 lymph node and there are microsatellite tumors, satellite tumors, and/or in-transit metastases on or under the skin; or
  • in 4 or more lymph nodes, or in any number of lymph nodes that are matted together; or
  • in 2 or more lymph nodes and/or in any number of lymph nodes that are matted together. There are microsatellite tumors, satellite tumors, and/or in-transit metastases on or under the skin.

    or

  (3) The tumor is more than 2 but not more than 4 millimeters thick, with ulceration, or more than 4 millimeters thick, without ulceration. Cancer is found in 1 or more lymph nodes and/or in any number of lymph nodes that are matted together. There may be microsatellite tumors, satellite tumors, and/or in-transit metastases on or under the skin.

  or

  (4) The tumor is more than 4 millimeters thick, with ulceration. Cancer is found in 1 or more lymph nodes and/or there are microsatellite tumors, satellite tumors, and/or in-transit metastases on or under the skin.

• Stage IIID: The tumor is more than 4 millimeters thick, with ulceration. Cancer is found:
  • in 4 or more lymph nodes, or in any number of lymph nodes that are matted together; or
  • in 2 or more lymph nodes and/or in any number of lymph nodes that are matted together. There are microsatellite tumors, satellite tumors, and/or in-transit metastases on or under the skin.

Stage IV

In stage IV, the cancer has spread to other parts of the body, such as the lung, liver, brain, spinal cord, bone, soft tissue (including muscle), gastrointestinal (GI) tract, and/or distant lymph nodes. Cancer may have spread to places in the skin far away from where it first started.

Melanoma can recur (come back) after it has been treated.

The cancer may come back in the area where it first started or in other parts of the body, such as the lungs or liver.