The TNM System (Tumor-Node-Metastasis) is the most widely used way of determining cancer stages. The TNM updated staging system, created by the AJCC (American Joint Committee on Cancer) provides important prognostic and survival information.Physicians use the TMN data to determine what treatments are appropriate.

 

The three most important distinguishing features of the primary tumor in determining stageare Tumor Thickness (also known as Breslow Depth), Ulceration, and Mitotic Count.

 

• Thickness or Tumor Depth is one of the most important factors in staging melanoma.  It is key in determining your treatment and prognosis.
• Ulceration occurs where the epidermis (top layer of the skin) covering the lesion is absent. This cannot usually be determined by the naked eye and can best be seen by a pathologist's examination of the tissue under a microscope. Ulcerated tumors have greater risk for metastatic disease.
• Mitotic Count is a measure of how many cells in a melanoma are actively dividing.

Tumor Depth

Is described in two ways:

Breslow Depth

Breslow depth measures in millimeters how thick the actual primary tumor is. It is measured in millimeters (1 mm= less than 1/16 inch). Breslow depth is measured starting at the outer layer of the epidermis downward to the deepest extension of the melanoma. The thicker the tumor is, the greater the chance it has metastasized or spread to regional lymph nodes or distant sties. It has replaced Clark Level as a more accurate measurement of tumor depth, and is more predictive of prognosis.

 

 

 

 

 

 

 

 

 

 

Clark Level

Clark Level describes how deeply the primary tumor has penetrated the different levels of the skin. The deeper the level of skin it has penetrated, the greater the chance that the tumor has metastasized to regional lymph nodes or distant sites. Clark level uses Roman numerals (I-V) (1-5) to determine the how far within the level the primary tumor has penetrated. Even though Clark Level has officially been dropped by the AJCC as a criteria in determining the stage of a melanoma, because it has been used for over 40 years it will likely continue in usage for some time.

 

 

 

 

 

 

 

 

 

 

 

 

About Breslow and Clark Levels

 

Clark Level is not considered as accurate as Breslow because the levels of skin thickness is not always the same throughout every part of body. It has been replaced by mitotic count, which is a more accurate predictor of survival in Stage I tumors that are no greater than 1.0 mm thick.

 

Codes Doctors Use to Describe Tumors

T for Tumor 

The "T" classifications are subdivided into smaller groups that describe, in more detail, about a patient's condition.  These are differentiated by the tumor's thickness, whether it has ulceration, and the Clark level.

 

TX: Tumor cannot be evaluated.
T0: Zero evidence of cancer.
Tis: Melanoma is "in situ" meaning it is still in the outer layer of skin and has not grown into other layers, and shows no signs of spreading.
T1: The primary tumor is 1.0 mm or thinner and one of the following:

• T1a: There is no ulceration and the mitotic count is less than 1mm².

• T1b: There is ulceration or the mitotic count is equal to or greater than 1mm².

T2: The primary tumor's thickness is between 1.01 mm and 2.0 mm and one of the following:

• T2a: There is no ulceration.

• T2b: There is ulceration.

T3: The primary tumor's thickness is between 2.01 mm and 4.0 mm and one of the following

• T3a: There is no ulceration.

  T3b: There is ulceration.

T4: The primary tumor is thicker than 4.0 mm and one of the following:

• T4a: There is no ulceration. 

• T4b: There is ulceration.

 

N for Nodes

This indicates whether there is evidence that the tumor has spread to surrounding lymph nodes. The number of lymph nodes to which the cancer has spread is important. When more lymph nodes have melanoma, there is reason for greater concern.

 

• The "N" in the TNM system stands for regional lymph nodes. Lymph nodes are small, bean-shaped structures that are full of immune cells. They filter the blood and help fight infection.

• Cancer spreads by using the lymphatic vessels that connect the lymph nodes. Often the first place that a cancer will spread will be to the closest lymph node (called the "sentinel lymph node").

The "N" classification tells you if melanoma cells have moved from the primary tumor into nearby lymph nodes. (Melanoma cells that are found along the lymphatic vessel but have not yet entered a lymph node are called "in-transit metastases" or "satellites.")

 

NX: regional (in the area near the melanoma primary site) lymph nodes cannot be evaluated.
N0: No evidence of spread to the lymph nodes.
N1: The melanoma has spread to 1 lymph node and one of the following:

• N1a: The doctor cannot feel cancer in the lymph nodes but can detect the cells when a sample is taken (microscopic metastasis).

• N1b: The doctor feels cancer in the lymph node or can see it on a scan (macroscopic metastasis).

N2: Melanoma has spread to 2 or 3 lymph nodes and one of the following:

• N2a: The doctor cannot feel a tumor in the lymph nodes but can see melanoma cells in a lymph node sample under the microscope (microscopic metastasis).

• N2b: The doctor can feel the tumor in the lymph nodes or see it on a scan (macroscopic metastasis).

• N2c: The doctor finds in-transit metastases or satellites without finding metastatic nodes.

N3: Any of the following conditions:

• The melanoma has spread to 4 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 (metastatic) lymph nodes.

 

M for Metastasis

This indicates the spread of cancer away from the original site. Usually, metastasis is used to describe the spread of a cancer into other organ systems and is associated with the more advanced stages of cancer.

 

• Having a tumor designated with an "M" means that the melanoma has spread beyond the primary melanoma site and the regional lymph nodes.

• The seriousness of the melanoma depends on where it has spread or metastasized to.

• In melanoma, metastasis can be found in the skin, under it, or in organs like the lung, liver, or brain.

• Metastases can be found in lymph nodes located beyond the primary tumor region; these are called distant lymph nodes.

• Micrometastases is the term used when the cancer in the lymph nodes is not visible to the naked eye and can only be detected through a biopsy.

• Macrometastases means the metastasis is large enough to be felt in a physical exam or seen by a surgeon

• Macrometastases have a more serious prognosis than micrometasteses.

 

A Test for Metastases - Level of Serum Lactate Dehydrogenase (LDH) - A general screening test used to look for evidence of cancer in other sites of the body is the blood LDH level. LDH is an enzyme found normally in the blood in small amounts and in many body tissues.

 

If the LDH level is high, this may indicate that there is a spread or metastasis of disease. An elevated LDH level usually will direct a doctor to perform more sensitive screening tests like a CT scan or an MRI.

 

The "M" classification tells you if melanoma cells have moved from the primary to distant sites in the body and where in the body they have moved to.

 

MX: Distant metastasis cannot be evaluated.
M0: The melanoma has not spread to distant sites.
M1a: The melanoma 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 melanoma has spread to the lungs.
M1c: The melanoma has spread to any other internal organ in the body other than the lungs and the LDH is normal OR there is distant spread to any site and the LDH is elevated.