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Stages of intraocular melanoma

Staging is a way of describing or classifying a cancer based on the extent of cancer in the body. The most common staging system for melanoma of the eye (intraocular) is the TNM system. The International Union Against Cancer (UICC) uses the TNM system to describe the extent of many solid tumour cancers.

Intraocular melanoma includes melanomas of the uvea of the eye, which includes the choroid, ciliary body and iris. The staging information below applies only to intraocular melanoma. Ocular lymphoma, orbital sarcoma, conjunctival tumours, lacrimal gland tumours and eyelid tumours are staged differently.

TNM

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

  • the size of the primary tumour
    • Melanoma of the iris has a different T category than melanoma of the ciliary body and choroid.
  • 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

Primary tumour (T) – intraocular melanoma of the iris

TX

Primary tumour cannot be assessed.

T0

No evidence of primary tumour.

T1

Tumour is limited to the iris.

T1a – Tumour is not more than 3 clock hours* in size.

T1b – Tumour is more than 3 clock hours in size.

T1c – There is increased pressure in the eye (secondary glaucoma) because of the cancer.

T2

Tumour joins or extends into the ciliary body, choroid or both.

T2a – Secondary glaucoma is present.

T3

Tumour joins or extends into the ciliary body, choroid or both, and extends into the sclera.

T3a – Secondary glaucoma is present.

T4

Tumour has spread outside the eyeball (extrascleral extension).

T4a – Tumour is 5 mm (0.2 inches) or less in diameter.

T4b – Tumour is more than 5 mm in diameter.

*Note: The iris is measured like a clock face. It is divided into twelve 30-degree sections equalling 360 degrees (or one clock face). Each 30-degree section is referred to as a clock hour. Also, if less than one-half of the tumour is located in the iris, the tumour may have started in the ciliary body and should be classified as a ciliary body melanoma.

Intraocular melanoma of the ciliary body and choroid

A size category of 1–4 is also used for ciliary body and choroidal melanomas based on the thickness (height) and largest diameter at the base of the tumour. The size category is used with the TNM classification for these ciliary body and choroid melanomas.

Size category
Thickness (mm)Category

greater than 15 (0.6 inches)

4

4

4

12.1–15.0

3

3

4

4

9.1–12.0

3

3

3

3

3

4

6.1–9.0

2

2

2

2

3

3

4

3.1–6.0

1

1

1

2

2

3

4

less than or equal to 3.0 (0.1 inches)

1

1

1

1

2

2

4

Largest diameter at the base of the tumour (mm)

less than or equal to 3.0 (0.1 inches)

3.1–6.0

6.1–9.0

9.1–12.0

12.1–15.0

15.1–18.0

greater than 18 (0.7 inches)

Primary tumour (T) – intraocular melanoma of the ciliary body and choroid

TX

Primary tumour cannot be assessed.

T0

No evidence of primary tumour.

T1

Tumour size category 1 and one of the following:

T1a – Tumour does not involve the ciliary body and has not spread outside the eyeball.

T1b – Tumour involves the ciliary body.

T1c – Tumour does not involve the ciliary body, but is growing outside the eyeball (extraocular spread). The part of the tumour outside the eyeball is 5 mm (0.2 inches) or less in diameter.

T1d – Tumour involves the ciliary body and is growing outside the eyeball (extraocular extension). The part of the tumour outside the eyeball is 5 mm or less in diameter.

T2

Tumour size category 2 and one of the following:

T2a – Tumour does not involve the ciliary body and has not spread outside the eyeball.

T2b – Tumour involves the ciliary body.

T2c – Tumour does not involve the ciliary body, but is growing outside the eyeball (extraocular spread). The part of the tumour outside the eyeball is 5 mm or less in diameter.

T2d – Tumour involves the ciliary body and is growing outside the eyeball (extraocular extension). The part of the tumour outside the eyeball is 5 mm or less in diameter.

T3

Tumour size category 3 and one of the following:

T3a – Tumour does not involve the ciliary body and has not spread outside the eyeball.

T3b – Tumour involves the ciliary body.

T3c – Tumour does not involve the ciliary body, but is growing outside the eyeball (extraocular spread). The part of the tumour outside the eyeball is 5 mm or less in diameter.

T3d – Tumour involves the ciliary body and is growing outside the eyeball (extraocular extension). The part of the tumour outside the eyeball is 5 mm or less in diameter.

T4

Tumour size category 4 and one of the following:

T4a – Tumour does not involve the ciliary body and has not spread outside the eyeball.

T4b – Tumour involves the ciliary body.

T4c – Tumour does not involve the ciliary body, but is growing outside the eyeball (extraocular spread). The part of the tumour outside the eyeball is 5 mm or less in diameter.

T4d – Tumour involves the ciliary body and is growing outside the eyeball (extraocular extension). The part of the tumour outside the eyeball is 5 mm or less in diameter.

T4e – Tumour is any size category and has grown more than 5 mm in diameter outside the eyeball.

Regional lymph nodes (N)

NX

Regional lymph nodes cannot be assessed

N0

No regional lymph node metastasis

N1

Regional lymph node metastasis

Note: The regional lymph nodes include those around the ear (preauricular nodes), lower jaw (submandibular nodes) and neck (cervical nodes).

Distant metastasis (M)

M0

No distant metastasis

M1

Distant metastasis

 

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Stage grouping for intraocular melanoma

The UICC further groups the TNM data into the stages listed in the table below.

UICC staging – intraocular melanoma
UICC stageTNM

stage I

T1a

N0

M0

stage IIA

T1b–d, T2a

N0

M0

stage IIB

T2b, T3a

N0

M0

stage IIIA

T2c–d, T3b–c, T4a

N0

M0

stage IIIB

T3d, T4b–c

N0

M0

stage IIIC

T4d–e

N0

M0

stage IV

any T

N1

M0

any T

any N

M1

Recurrent intraocular melanoma

Recurrent intraocular 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 intraocular melanoma).

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COMS classification

The Collaborative Ocular Melanoma Study (COMS) group developed a size classification for the prognosis and treatment of intraocular melanoma. The COMS classification may be used when discussing and planning treatment of intraocular melanoma because it is easier to understand than the TNM system.

The size of the tumour is measured by its height (thickness) and basal diameter (diameter or length at the base of the tumour).

Size classificationHeight (mm)Basal diameter (mm)

small

1.0–2.5

5 or less

medium

2.5–10

5–16

large

10 or greater

16 or greater

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