Staging is a way of describing a cancer, such as where it is located, if or where it has spread, and if it is affecting the functions of other organs in the body. Doctors use diagnostic tests to determine a cancer's stage, so staging may not be complete until all of the tests are finished. Knowing the stage helps the doctor to decide what kind of treatment is best and can help predict a patient’s prognosis (chance of recovery). There are different stage descriptions for different types of cancer.
To determine the stage of a melanoma, the lesion and some surrounding normal tissue need to be surgically removed and analyzed using a microscope. Doctors use the melanoma’s thickness, measured in millimeters (mm), to help determine the disease’s stage. The original melanoma is often called the primary melanoma or primary tumor.
One tool that doctors use to describe the stage is the TNM system. This system uses three criteria to judge the stage of the cancer: the tumor itself, the regional lymph nodes around the tumor, and if the tumor has spread to other parts of the body. The results are combined to determine the stage of cancer 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 treatments.
TNM is an abbreviation for tumor (T), node (N), and metastasis (M). Doctors look at these three factors to determine the stage of cancer:
- How large is the primary tumor and where is it located? (T)
- Has the tumor spread to the regional lymph nodes, or is there evidence of in-transit metastases or satellites (defined below)? (N)
- Has the cancer metastasized to other (distant) parts of the body? (M)
Tumor. Using the TNM system, the "T" plus a letter and/or number (0 to 4) is used to describe the primary melanoma, particularly its size.
If the outer layer of skin (the epidermis) does not appear under a microscope to be overlying the melanoma, that is referred to as ulceration. In addition, the doctor may also refer to the Clark’s level of the tumor, which is a specific classification to describe how deep the melanoma has grown into the layers of skin. The Clark’s level also uses Roman numerals (I, II, III, IV,V; one to five) in its description.
Based on the size, ulceration, and Clark’s level, some T classifications are subdivided into smaller groups that help describe the tumor in even more detail. Tumor classification information is listed below.
TX: The tumor cannot be evaluated.
T0: There is no evidence of cancer.
Tis: Called melanoma in situ, which means that cancer cells are found in only the outer layer of skin (epidermis) and has not grown into any other layers. The cancer cells do not show signs of spreading.
T1: The primary tumor is 1.0 mm or thinner, and one of the following:
T1a: The primary tumor has no ulceration and Clark's level II or III.
T1b: The primary tumor has ulceration or Clark's level IV or V.
T2: The primary tumor’s thickness is between 1.0 mm and 2.0 mm, and one of the following:
T2a: The primary tumor has no ulceration.
T2b: The primary tumor has ulceration.
T3: The primary tumor’s thickness is between 2.0 mm and 4.0 mm, and one of the following:
T3a: The primary tumor has no ulceration.
T3b: The primary tumor has ulceration.
T4: The primary tumor is thicker than 4.0 mm, and one of the following:
T4a: The primary tumor has no ulceration.
T4b: The primary tumor has ulceration.
Node. The "N" in the TNM system stands for regional lymph nodes. In addition, the “N” classification includes whether small deposits of melanoma are found between the primary tumor and the regional lymph nodes (called in-transit metastases or satellites).
NX: The regional lymph nodes cannot be evaluated.
N0: There is no evidence of cancer in the lymph nodes.
N1: The cancer has spread to one lymph node, and one of the following:
N1a: The doctor cannot feel cancer in the lymph nodes but can detect cancer cells in a lymph
node sample when viewed under a microscope (called microscopic metastasis).
N1b: The doctor can feel the cancer in the lymph nodes or see it on a scan (called macroscopic
metastasis).
N2: Cancer has spread to two or three lymph nodes, and one of the following:
N2a: The doctor cannot feel cancer in the lymph nodes but can detect cancer cells in a lymph
node sample when viewed under a microscope.
N2b: The doctor can feel the cancer in the lymph nodes or see it on a scan.
N2c: The doctor finds in-transit metastases or satellites.
N3: Any of the following conditions:
- The cancer has spread to four or more lymph nodes.
- Two or more lymph nodes appear joined together (called matted lymph nodes).
- In-transit metastases or satellites are present, with any number of affected lymph nodes.
Distant metastasis. The "M" in the TNM system indicates whether melanoma has spread to other parts of the body, beyond the primary melanoma site and the regional lymph nodes. In melanoma, metastasis may be found in the skin, subcutaneous tissue (under the skin), or in other organs such as the lung, liver or brain. Lymph nodes beyond the primary tumor region are called distant lymph nodes.
MX: Distant metastasis cannot be evaluated.
M0: The melanoma has not spread to distant sites.
M1a: The cancer has spread outside the region where it first started to other parts of the skin, under the skin, or any distant lymph nodes.
M1b: The cancer has spread to the lungs.
M1c: The cancer has spread to any other internal organ in the body. Also, any distant metastasis combined with a blood test result showing an elevated level of a tumor marker called LDH is classified as MIc. A tumor marker is a substance found in a patient’s blood that is produced either by the tumor itself or by the body in response to the cancer.
Melanoma stage grouping
Doctors determine the stage of the melanoma by combining the T, N, and M classifications.
Stage 0: Refers to melanoma in situ (melanoma cells are found only in the outer layer of skin).
Stage IA: The melanoma is 1.0 mm or thinner, has no ulceration, and is Clark's level II or III.
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Stage IB: Describes either of these conditions:
- The melanoma is 1.0 mm or thinner, and either has ulceration and/or Clark's level IV or V.
- The melanoma is between 1.0 mm and 2.0 mm and has no ulceration.
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Stage IIA: Describes either of these conditions:
- The melanoma is between 1.0 mm and 2.0 mm and has ulceration.
- The melanoma is between 2.0 mm and 4.0 mm and has no ulceration.
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Stage IIB: Describes either of these conditions:
- The melanoma is between 2.0 mm and 4.0 mm and has ulceration.
- The melanoma is larger than 4.0 mm and has no ulceration.
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Stage IIC: The melanoma is larger than 4.0 mm and has ulceration.
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Stage III: The melanoma is of any thickness, and melanoma has spread to one or more regional lymph nodes and/or there is in-transit or satellite involvement. However, the melanoma has not spread to distant parts of the body.
Stage IIIA: The primary melanoma has no ulceration and has spread to up to three lymph nodes in the form of micrometastases.
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Stage IIIB: Describes any of these conditions:
- The melanoma has spread to up to three regional lymph nodes in the form of macrometastases and the primary melanoma has no ulceration.
- The melanoma has spread to up to three regional lymph nodes, but is still microscopic and the primary melanoma has ulceration.
- There is in-transit or satellite involvement without regional lymph node spread.
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Stage IIIC: Describes any of these conditions:
- The melanoma has spread to up to three regional lymph nodes, the lymph nodes show macrometastases, and the primary tumor has ulceration.
- The melanoma has spread to four or more regional lymph nodes.
- The melanoma has in-transit or satellite involvement and has spread to any of the lymph nodes.
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Stage IV: The primary melanoma has spread to other, distant parts of the body beyond the regional lymph nodes. This is regardless of the primary tumor’s thickness and whether it has spread to any of lymph nodes or satellite or in-transit sites.
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Recurrent: Recurrent melanoma is melanoma that comes back after treatment.
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, Sixth Edition (2002) published by Springer-Verlag New York, www.cancerstaging.net.
Last Updated: May 28, 2009
