Melanoma

Our staging illustrations are currently being updated to comply with the new 2010 American Joint Committee on Cancer staging guidelines. We apologize for the inconvenience.

Staging is a way of describing a cancer, such as where it is located, if or where it has spread, and whether it is affecting the functions of other organs in the body. Doctors may use diagnostic tests (see Diagnosis)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 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.) 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 judges three factors: the tumor itself, the regional lymph nodes near 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 of melanoma: 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 thick 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.

The pathologist will measure the thickness of the melanoma in millimeters. Other important features of the melanoma include the mitotic rate (the speed at which tumor cells are dividing) per millimeter squared (mm²) and the presence or absence of ulceration (see Diagnosis). “a” and “b” T- subcategories are assigned based on ulceration and number of mitosis per mm².

The T classifications are based on the thickness, the presence or absence of ulceration, and the mitotic rate. Tumor classification information is listed below:

TX: The tumor cannot be evaluated.

T0: There is no evidence of a primary tumor.

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 a mitotic rate less than 1/mm².

T1b: The primary tumor has ulceration and/or a mitotic rate equal to or greater than 1/mm².

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 in the lymph channels between the primary tumor and the regional lymph nodes (called in-transit metastases or satellites), either on the skin (cutaneous) or under the skin (subcutaneous).

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.
• Multiple lymph nodes appear joined together (called matted lymph nodes).
• In-transit metastases or satellites are present, with at least one 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 distant parts of the skin, distant locations 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 (see Diagnosis) is classified as MIc.

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 has a mitotic rate less than 1/mm².

Stage IB: Describes either of these conditions:

• The melanoma is 1.0 mm or thinner and has ulceration and a mitotic rate equal to or greater than 1/mm².
• The melanoma is between 1.0 mm and 2.0 mm and has no ulceration.

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.

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.

Stage IIC: The melanoma is larger than 4.0 mm and has ulceration.

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.

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.

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.
• The location of the primary tumor is unknown, and there are isolated metastases in lymph nodes, skin, and tissues under the skin.

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.

Recurrent: Recurrent melanoma is melanoma that comes back after treatment. If there is a recurrence, the cancer may need to be staged again (re-staging) using the system above.

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.