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Melanoma

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Stages of melanoma

Staging is a way of describing or classifying a cancer based on the extent of cancer in the body. Staging is commonly used to plan treatment. The most common staging system for melanoma is the TNM system. Melanoma is also put into stage groupings ( 0, I, II, III, IV) based on TNM.

TNM staging

TNM stands for tumour, nodes, metastasis. TNM staging describes:

  • the size of the primary tumour
  • the number and location of any regional lymph nodes that have cancer cells in them
  • whether the cancer has spread or metastasized to another part of the body
  • whether or not there is ulceration
    • A melanoma is said to be ulcerated if the layer of skin covering the melanoma is not clearly seen.

Primary tumour (T)

TX

Primary tumour cannot be assessed

T0

No evidence of primary tumour

Tis

Melanoma in situ

T1

Melanomas 1.0 mm or less in thickness

T1a

No ulceration and mitosis less than 1/mm2

T1b

Ulceration or mitosis equal to or greater than 1/mm2

T2

Melanomas 1.01–2.0 mm

T2a

No ulceration

T2b

Ulceration

T3

Melanomas 2.01–4.0 mm

T3a

No ulceration

T3b

Ulceration

T4

Melanomas more than 4.0 mm

T4a

No ulceration

T4b

Ulceration

Lymph node staging

There are two methods to stage melanoma in the lymph nodes:

  • Clinical staging of lymph nodes is based on the physical examination and any imaging tests done. The clinical staging of lymph nodes is done before a sentinel lymph node biopsy and is categorized as N1, N2 or N3.
  • Pathological staging of lymph nodes uses all the information from clinical staging, plus what is found from the biopsy of lymph nodes. The pathological staging is subdivided into Na, Nb and Nc.
    • Na - the cancer can only be seen under a microscope
    • Nb - means the cancer is clinically detectable in the lymph node
    • Nc -  there is satellite or in-transit disease

Regional lymph nodes (N)

NX

Regional lymph nodes cannot be assessed

N0

No regional lymph node metastasis

N1

Metastasis to one node

N1a

Micrometastasis (the doctor cannot feel cancer in the lymph nodes but there are cancer cells in a lymph node sample viewed under a microscope)

N1b

Macrometastasis (the doctor can feel cancer in the lymph nodes or see it in a scan)

N2

Metastasis to 2 or 3 nodes

N2a

Micrometastasis

N2b

Macrometastasis

N2c

Satellite (metastasis found within 2 cm of the primary tumour) or in-transit metastasis (skin or subcutaneous tissue involvement more than 2 cm from the primary tumour but not beyond the regional lymph nodes) without metastatic lymph nodes

N3

Metastasis in 4 or more lymph nodes, matted (not moveable) lymph nodes or in-transit metastasis or satellite(s) with metastatic lymph node(s)

Distant metastasis (M)

M0

No detectable evidence of distant metastases

M1

Distant metastasis

M1a

Metastasis to distant skin, distant subcutaneous or distant lymph nodes with a normal serum lactate dehydrogenase (LDH)lactate dehydrogenase (LDH)An enzyme that is involved in energy production in cells. level

M1b

Metastasis to lung with a normal serum LDH level

M1c

Metastasis to internal organs other than the lung with a normal serum LDH level or a constant elevated serum LDH level with distant metastasis, regardless of the site

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Stage groupings for melanoma

The UICC and American Joint Committee on Cancer (AJCC) further group the TNM data into the stages listed in the table below.

UICC/AJCC staging – melanoma
UICC/AJCC stageTNMExplanation

stage 0

Tis

N0

M0

In situ melanoma – the melanoma is confined to the epidermis (very top layer of skin) and has not spread to the dermis

stage IA

T1a

N0

M0

Melanoma is less than 1 mm thick and is not ulcerated.

Melanoma has not spread to lymph nodes or distant sites.

stage IB

T1b or T2a

N0

M0

Melanoma is less than 1 mm thick and is ulcerated, or melanoma is 1.01–2.0 mm thick and is not ulcerated.

Melanoma has not spread to lymph nodes or distant sites.

stage IIA

T2b or T3a

N0

M0

Melanoma is 1.01–2.0 mm thick and is ulcerated, or is 2.01–4.0 mm thick and is not ulcerated.

Melanoma has not spread to lymph nodes or distant sites.

stage IIB

T3b or T4a

N0

M0

Melanoma is 2.01–4.0 mm thick and is ulcerated, or is thicker than 4.0 mm and is not ulcerated.

Melanoma has not spread to lymph nodes or distant sites.

stage IIC

T4b

N0

M0

Melanoma is thicker than 4.0 mm and is ulcerated.

Melanoma has not spread to lymph nodes or distant sites.

stage IIIA

T1a–4a

N1a, N2a

M0

Melanoma is any thickness and is not ulcerated.

Melanoma has spread to 1–3 lymph nodes nearby, but spread can only be found by examination under a microscope and the lymph nodes are not enlarged.

No distant spread.

stage IIIB

T1b–4b

N1a, N2a

M0

Melanoma is any thickness and is ulcerated.

Melanoma has spread to 1–3 lymph nodes nearby, but spread can only be found by examination under a microscope and the lymph nodes are not enlarged.

No distant spread.

T1a–4a

N1b, N2b

M0

Melanoma is any thickness and is not ulcerated.

Melanoma has spread to 1–3 lymph nodes nearby, the lymph nodes are enlarged.

No distant spread.

T1a–4a

N2c

M0

Melanoma is any thickness and is not ulcerated.

Melanoma has spread to small areas of nearby skin or lymph vessels in the skin around the tumour.

The lymph nodes do not contain melanoma.

No distant spread.

stage IIIC

T1b–4b

N1b

M0

Melanoma is any thickness and is ulcerated.

Melanoma has spread to one lymph node nearby and the lymph node is enlarged.

No distant spread.

T1b–4b

N2b

M0

Melanoma is any thickness and is ulcerated.

Melanoma has spread to 2–3 lymph nodes nearby and the lymph nodes are enlarged.

No distant spread.

T1b–4b

N2c

M0

Melanoma is any thickness and is ulcerated.

Melanoma has spread to small areas of nearby skin or lymph vessels in the skin around the tumour.

The lymph nodes do not contain melanoma.

No distant spread.

any T

N3

M0

Melanoma is ulcerated.

Melanoma has spread to 4 or more lymph nodes nearby or to lymph vessels in the skin around the tumour and any number of lymph nodes, and the lymph nodes are enlarged.

No distant spread.

stage IV

any T

any N

M1

Melanoma has spread beyond the original site to other organs or to distant areas of the skin or distant lymph nodes

Recurrent melanoma

Recurrent melanoma means that the cancer has come back after it has been treated. It may recur in the same location as the original cancer or it may recur in another part of the body (metastatic melanoma).

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Classification of melanoma

There are 2 different classification systems for melanoma.

Breslow’s classification

Breslow’s classification is a measurement of how deeply the melanoma has grown into the skin. The tumour thickness (depth) is usually measured from the top of the tumour to the deepest cells. Breslow’s depth or thickness is used in TNM staging for melanoma.

Clark’s classification

Clark’s classification describes how deeply the melanoma penetrates into the skin. It does not measure the tumour. The Clark level of a melanoma uses a scale of I–V.

Clark’s classification of melanoma
Clark levelDescription

I

Melanoma involves only the epidermis (in situin situ1. Occurring in the normal or natural place. 2. Confined to the original site or position. melanoma).

II

Melanoma extends to the upper dermis (papillary dermis), but does not reach the border of the reticular dermis.

III

Melanoma extends to the border of the papillary and lower dermis (reticular dermis), but does not penetrate the reticular dermis.

IV

Melanoma involves the lower dermis (reticular dermis) but not the subcutaneous tissue.

V

Melanoma extends through the reticular dermis into the subcutaneous tissue.

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