Melanoma: Stages

Aprobado por la Junta Editorial de Cancer.Net, 12/2021

ON THIS PAGE: You will learn about how doctors describe a melanoma’s growth or spread. This is called the stage. Use the menu to see other pages.

What is cancer staging?

Staging is a way of describing where the cancer is located, if or where it has spread, and whether it is affecting other parts of the body.

Doctors use diagnostic tests to find out the cancer's stage, so staging may not be complete until all of the tests are finished. Knowing the stage helps the doctors recommend the best type of treatment, and it can help predict a patient's prognosis, which is the chance of recovery. There are different stage descriptions for different types of cancer.

This page provides detailed information about the system used to find the stage of melanoma and the stage groups for melanoma, such as stage II or stage IV.

Factors used for staging melanoma

To determine the stage of a melanoma, the lesion and some surrounding healthy tissue need to be surgically removed and analyzed using a microscope. Doctors use the melanoma’s thickness, measured in millimeters (mm), and the other characteristics described in Diagnosis to help determine the disease’s stage.

Doctors also use results from diagnostic tests and surgical procedures to answer these questions about the stage of melanoma:

  • How thick or deep is the primary melanoma?
  • Where is the melanoma located?
  • Has the melanoma spread to the lymph nodes? If so, where and how many?
  • Has the melanoma metastasized to other parts of the body? If so, where and how much?

The results are combined to determine the stage of melanoma for each person. The stages of melanoma include: stage 0 (zero) and stages I through IV (1 through 4). The stage provides a common way of describing the cancer, so doctors can work together to create the best treatment plan and understand a patient's prognosis.

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Stage groups for melanoma

Stage 0: This refers to melanoma in situ, which means melanoma cells are found only in the outer layer of skin or epidermis. This stage of melanoma is very unlikely to spread to other parts of the body.The melanoma has not spread to any lymph nodes.

Stage I: The primary melanoma is still only in the skin and is relatively thin. Stage I is divided into 2 subgroups, IA or IB, depending on the thickness of the melanoma and whether a pathologist sees ulceration under a microscope. The melanoma has not spread to any lymph nodes.

Stage II: Stage II melanoma is thicker than stage I melanoma, extending through the epidermis and further into the dermis, the dense inner layer of the skin. The melanoma has not spread to any lymph nodes, but it has a higher chance of spreading. Stage II is divided into 3 subgroups—A, B, or C—depending on how thick the melanoma is and whether there is ulceration.

Stage III: Stage III melanoma has spread locally or through the lymphatic system to a regional lymph node located near where the cancer started or to a skin site on the way to a lymph node, called in-transit metastasis, satellite metastasis, or microsatellite disease. The lymphatic system is part of the immune system and drains fluid from body tissues through a series of tubes or vessels. Stage III is divided into 4 subgroups—A, B, C, or D—depending on the thickness of the tumor, the size and number of lymph nodes involved with melanoma, whether the primary tumor has satellite or in-transit lesions, and if it appears ulcerated under a microscope.

Stage IV: This stage describes melanoma that has spread through the bloodstream to other parts of the body, such as distant locations on the skin or soft tissue, distant lymph nodes, or other organs like the lung, liver, brain, bone, or gastrointestinal tract. Stage IV is further evaluated based on the location of distant metastasis:

  • M1a: The cancer has only spread to distant skin and/or soft-tissue sites.

  • M1b: The cancer has spread to the lung.

  • M1c: The cancer has spread to any other location that does not involve the central nervous system.

  • M1d: The cancer has spread to the central nervous system, including the brain, spinal cord, and/or cerebrospinal fluid, or lining of the brain and/or spinal cord.

Recurrent: Recurrent melanoma is melanoma that has come back after treatment. If the melanoma does return, there will be a round of tests to learn about the extent of the recurrence. These tests and scans may be similar to those done at the time of the original diagnosis.

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Used with permission of the American College of Surgeons, Chicago, Illinois. The original and primary source for this information is the AJCC Cancer Staging Manual, Eighth Edition (2017), published by Springer International Publishing.

Information about the cancer’s stage will help the doctor recommend a specific treatment plan. The next section in this guide is Types of Treatment. Use the menu to choose a different section to read in this guide.