ON THIS PAGE: You will learn about how doctors describe a melanoma’s growth or spread. This is called the stage. To see other pages in this guide, use the colored boxes on the right side of your screen, or click “Next” at the bottom.
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 determine the cancer's stage, so staging may not be complete until all of the tests are finished. Knowing the stage helps the doctors decide what type of treatment is best and can help predict a patient's prognosis. There are different stage descriptions for different types of cancer.
To determine the stage of a melanoma, the lesion and some surrounding healthy tissue needs to be surgically removed and analyzed using a microscope. Doctors use the melanoma’s thickness, measured in millimeters (mm), and other characteristics to help determine the disease’s stage. (These factors are explained in the Diagnosis  section.)
Doctors look at these three factors to determine the stage of melanoma:
- How large is the original melanoma (often called the primary melanoma or primary tumor), and where is it located?
- Has the melanoma spread to the lymph nodes?
- Has the melanoma metastasized to other parts of the body?
The results are combined to determine the stage of melanoma for each person. There are five stages: stage 0 (zero) and stages I through IV (one through four). The stage provides a common way of describing the cancer, so doctors can work together to plan the best treatment plan and understand a patient's prognosis when diagnosed.
Here are more details about each stage of melanoma.
Stage 0: This refers to melanoma in situ, which means melanoma cells are found only in the epidermis (the outer layer of skin). This stage of melanoma has virtually no metastatic potential, which means it is very unlikely that it will spread to other parts of the body.
Stage I: The melanoma is still only in the skin and is very thin. Stage IA melanoma is 1.0 mm or thinner and has no ulceration. Stage IB may describe a melanoma that is the same thickness but has ulceration or a melanoma that is slightly thicker (between 1.1 mm and 2.0 mm) with no ulceration.
Stage II: Stage II melanoma is thicker than stage I melanoma, extending through the epidermis and into the dermis (dense inner layer of the skin), and it has a slightly higher chance of spreading. Stage II is divided into three smaller groups—A, B, or C—depending on how thick the melanoma is and whether or not there is ulceration.
Stage III: This stage describes melanoma that has spread through the lymphatic system (part of the immune system and drains fluid from body tissues through a series of tubes) either to a regional lymph node (lymph nodes near where the cancer started) or to a skin site on the way to a lymph node (“in-transit metastasis”). Stage III is also divided into substages—A, B, or C—depending on the size and number of lymph nodes involved with melanoma.
Stage IV: This stage describes melanoma that has spread through the bloodstream to other, distant parts of the body, such as the lung, liver, brain, bone, or gastrointestinal tract. Stage IV is further divided into M1a (metastasis only to the skin and/or soft tissue sites), M1b (metastasis to the lung), and M1c (metastasis anywhere else).
Recurrent: Recurrent melanoma is melanoma that has come back after treatment. If there is a recurrence, the cancer may need to be staged again (re-staging).
Used with permission of the American Joint Committee on Cancer (AJCC), Chicago, Illinois. The original source for this material is the AJCC Cancer Staging Manual, Seventh Edition (2010) published by Springer-Verlag New York, www.cancerstaging.net .
Information about the cancer’s stage will help the doctor recommend a treatment plan for you. Choose “Next” (below, right) to continue reading about treatment options for this type of cancer. Or, use the colored boxes located on the right side of your screen to visit any section.