After melanoma has been diagnosed, tests are 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. Talk with your doctor about what the stage of your cancer is. The following tests and procedures may be used in the staging process:
- Physical exam and history: An exam of the body to check general signs of health, including checking for signs of disease, such as lumps or anything else that seems unusual. A history of the patient’s health habits and past illnesses and treatments will also be taken.
- 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).
- 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). LDH levels that are higher than normal may be a sign of 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 method used to stage melanoma is based mainly on the thickness of the tumor and whether cancer has spread to lymph nodes or other parts of the body.The staging system is based on the following:
- The thickness of the tumor. The thickness is described using the Breslow scale.
- Whether the tumor is ulcerated (has broken the skin).
- Whether the tumor has spread to the lymph nodes and if the lymph nodes are joined together (matted).
- Whether the tumor has spread to other parts of the body.
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.
In stage I, cancer has formed. Stage I is divided into stages IA and IB.
Stage II is divided into stages IIA, IIB, and IIC.
In stage III, the tumor may be any thickness, with or without ulceration. One or more of the following is true:
- Cancer has spread to one or more lymph nodes.
- Lymph nodes may be joined together (matted).
- Cancer may be in a lymph vessel between the primary tumor and nearby lymph nodes.
- Very small tumors may be found on or under the skin, not more than 2 centimeters away from where the cancer first started.
In stage IV, the cancer has spread to other places in the body, such as the lung, liver, brain, bone, soft tissue, or gastrointestinal (GI) tract. Cancer may have spread to places in the skin far away from where it first started.