Eye Melanoma: Stages and Grades

Approved by the Cancer.Net Editorial Board, 01/2023

ON THIS PAGE: You will learn about how doctors describe a cancer’s growth or spread, as well as the way the tumor cells look when viewed under a microscope. This is called the stage and grade. Use the menu to see other pages.

What is cancer staging?

Staging is a way of describing where the cancer is located, if or where it has spread, and whether it is affecting other parts of the body.

Doctors use diagnostic tests to find out the cancer's stage, so staging may not be complete until all of the tests are finished. Knowing the stage helps the doctor recommend the best kind of treatment, and it can help predict a patient's prognosis, which is the chance of recovery. There are different stage descriptions for different types of cancer.

Staging can be clinical or pathological. Clinical staging is based on the results of tests done before surgery, which may include physical examinations and imaging tests. Pathological staging is based on what is found during surgery, including a biopsy. In general, pathological staging provides the most information to determine a patient’s prognosis.

This page provides detailed information about the system used to find the stage of eye melanoma and the stage groups for eye melanoma, such as stage I or stage IIIB.

TNM staging system for uveal melanoma

One tool that doctors use to describe the stage is the TNM system. Medical oncologists use this system, but your ophthalmologist may not. Talk with your doctor about the description of your tumor. Doctors use the results from diagnostic tests and scans to answer these questions:

  • Tumor (T): How large is the primary tumor? Where is it located?

  • Node (N): Has the tumor spread to the lymph nodes? If so, where and how many?

  • Metastasis (M): Has the cancer spread to other parts of the body? If so, where and how much?

The results are combined to determine the stage of cancer for each person.

There are 5 stages of uveal melanoma: stage 0 (zero) and stages I through IV (1 through 4). The stage provides a common way of describing the cancer, so doctors can work together to plan the best treatments. Ophthalmologists who do not use the TNM system to stage uveal melanoma still consider the size of the tumor when deciding on a treatment plan. They also consider how the tumor is affecting a person’s vision.

For uveal melanoma, T for an iris melanoma is described differently than T for choroidal and ciliary body melanomas and conjunctival melanomas. N and M are described the same for iris, choroidal, and ciliary body melanomas. They are described differently for conjunctival melanoma.

Tumor (T)

Using the TNM system, the "T" plus a letter or number (0 to 4) is used to describe the size and location of the tumor. Tumor size is measured in centimeters (cm). A centimeter is roughly equal to the width of a standard pen or pencil.

Stage may also be divided into smaller groups that help describe the tumor in even more detail. The following classifications are the same for any type of uveal melanoma:

TX: The primary tumor cannot be evaluated.

T0: There is no tumor in the eye.

Iris melanoma

An iris tumor is classified as T1, T2, T3, or T4. Each classification may also be divided into smaller groups that help describe the tumor in even more detail.

T1: The tumor is limited to the iris.

  • T1a: The tumor is in 1 quadrant (one-fourth) or less of the iris.

  • T1b: The tumor is in more than 1 quadrant of the iris.

  • T1c: The tumor is only in the iris, but there is melanomalytic glaucoma. This means that a buildup of certain cells in the eye blocks the flow of fluid in the eye, which causes pressure.

T2: The tumor has joined or grown into the ciliary body and/or choroid.

  • T2a: The tumor has joined or grown into the ciliary body.

  • T2b: The tumor has joined or grown into the ciliary body and choroid.

  • T2c: The tumor has joined or grown in the ciliary body and/or choroid and is causing melanomalytic glaucoma.

T3: The tumor has joined or grown into the ciliary body and/or choroid and extends to the sclera.

  • T3a: The tumor has joined or grown into the ciliary body and/or choroid and extends to the sclera in association with melanomalytic glaucoma.

T4: The tumor has spread to the outside of the eyeball, the optic nerve, or the eye socket. This is called extraocular extension.

  • T4a: The tumor has spread less than 5 millimeters (mm) outside of the eye.

  • T4b: The tumor has spread more than 5 mm outside of the eye.

Ciliary body and choroid melanoma

A tumor in the ciliary body and choroid is also classified as T1, T2, T3, or T4 based on the size of the tumor. The size is measured in optic disc diameters or millimeters. The tumor is measured for both width and height. This is also called thickness. A tumor is given a classification according to the table below, based on its width and height.

Your doctors may use and refer to this classification, called a category, even more than the stage. This is because the size and thickness of the tumor (the T) is most important for finding out a patient’s prognosis.

Size Category Classification Table for Ciliary Body and Choroid Melanoma

Thickness (mm)

Category

Thicker than 15 mm

4

4

4

12.1 to 15.0

3

3

4

4

9.1 to 12.0

3

3

3

3

3

4

6.1 to 9.0

2

2

2

2

3

3

4

3.1 to 6.0

1

1

1

2

2

3

4

Less than 3.0

1

1

1

1

2

2

4

Largest basal diameter (mm)

Less than 3.0 mm

3.1 to 6.0 mm

6.1 to 9.0 mm

9.1 to 12.0 mm

12.1 to 15.0 mm

15.1 to 18.0 mm

Larger than 18.0 mm

Used with permission of the American Joint Committee on Cancer (AJCC), Chicago, Illinois.

T1: The tumor is size category 1.

  • T1a: The tumor is size category 1 and does not involve the ciliary body or other parts of the eye.

  • T1b: The tumor is size category 1 and involves the ciliary body.

  • T1c: The tumor is size category 1 that does not involve the ciliary body, but there is a very small area (5 mm or less in diameter) of visible spread beyond the eyeball. This is called extraocular spread.

  • T1d: The tumor is size category 1 that involves the ciliary body with extraocular spread less than 5 mm.

T2: The tumor is size category 2.

  • T2a: The tumor is size category 2 and does not involve the ciliary body or other parts of the eye.

  • T2b: The tumor is size category 2 and involves the ciliary body.

  • T2c: The tumor is size category 2 that does not involve the ciliary body, but there is a very small area (5 mm or less in diameter) of visible spread beyond the eyeball.

  • T2d: The tumor is size category 2 that involves the ciliary body with extraocular spread less than 5 mm.

T3: The tumor is size category 3.

  • T3a: The tumor is size category 3 and does not involve the ciliary body or other parts of the eye.

  • T3b: The tumor is size category 3 and involves the ciliary body.

  • T3c: The tumor is size category 3 that does not involve the ciliary body, but there is a very small area (5 mm or less in diameter) of visible spread beyond the eyeball.

  • T3d: The tumor is size category 3 that involves the ciliary body with extraocular spread less than 5 mm.

T4: The tumor is size category 4.

  • T4a: The tumor is size category 4 and does not involve the ciliary body or other parts of the eye.

  • T4b: The tumor is size category 4 and involves the ciliary body.

  • T4c: The tumor is size category 4 that does not involve the ciliary body, but there is a very small area (5 mm or less in diameter) of visible spread beyond the eyeball.

  • T4d: The tumor is size category 4 that involves the ciliary body with extraocular spread less than 5 mm.

  • T4e: The tumor is any size category with extraocular spread of more than 5 mm in diameter.

Conjunctival melanoma

A tumor in the conjunctiva is also classified as T1, T2, T3, or T4 based on the size of the tumor. The following are the classifications for conjunctival melanoma:

T1: The tumor is in the bulbar conjunctiva.

  • T1a: The tumor is in less than 1 quadrant of the bulbar conjunctiva.

  • T1b: The tumor is in at least 1 quadrant of the bulbar conjunctiva but not more than 2.

  • T1c: The tumor is in at least 2 quadrants of the bulbar conjunctiva but not more than 3.

  • T1d: The tumor is in at least 3 quadrants of the bulbar conjunctiva.

T2: The tumor is in the nonbulbar conjunctiva and has possibly spread to the caruncle, which is the small, pink spot in the inner corner of the eye.

  • T2a: The tumor is in at most 1 quadrant of the nonbulbar conjunctiva and has not spread to the caruncle.

  • T2b: The tumor is in more than 1 quadrant of the nonbulbar conjunctiva and has not spread to the caruncle.

  • T2c: The tumor is in at most 1 quadrant of the nonbulbar conjunctiva and has spread to the caruncle.

  • T2d: The tumor is in more than 1 quadrant of the nonbulbar conjunctive and has spread to the caruncle.

T3: The tumor is any size and has spread to nearby structures of the eye.

  • T3a: The tumor has spread to the globe.

  • T3b: The tumor has spread to the eyelid.

  • T3c: The tumor has spread to the orbit.

  • T3d: The tumor has spread to the nasolacrimal duct, lacrimal sac, and/or paranasal sinuses.

T4: The tumor is any size and has spread to the central nervous system.

Node (N)

The “N” in the TNM staging system stands for lymph nodes. These small, bean-shaped organs help fight infection. Lymph nodes near where the cancer started are called regional lymph nodes. Lymph nodes in other parts of the body are called distant lymph nodes. N is described the same for melanomas of the iris, ciliary body, choroid, and conjunctiva. However, for conjunctival melanoma, N1a and N1b do not apply.

NX: The regional lymph nodes cannot be evaluated.

N0 (N zero): The cancer has not spread to the regional lymph nodes.

N1: The cancer has spread to regional lymph nodes or the cancer has spread elsewhere.

  • N1a: The cancer has spread to regional lymph nodes.

  • N1b: The cancer has not spread to regional lymph nodes, but it has spread to other parts of the eye.

Metastasis (M)

The “M” in the TNM system describes whether the cancer has spread to other parts of the body, which is called metastasis. M is described the same for iris, ciliary body, choroidal, and conjunctival melanomas. However, for conjunctival melanoma, M1a, M1b, and M1c do not apply.

MX: Distant metastasis cannot be evaluated.

M0 (M zero): There is no distant metastasis.

M1: There is metastasis to other parts of the body.

  • M1a: There is metastasis to other parts of the body and the largest metastasis is 3 centimeters (cm) or less in diameter.

  • M1b: There is metastasis to other parts of the body and the largest metastasis is between 3.1 cm and 8 cm in diameter.

  • M1c: There is metastasis to other parts of the body and the largest metastasis is larger than 8.1 cm in diameter.

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Grade (G) and histopathology

Doctors also describe eye melanoma by its grade (G). The grade describes how much cancer cells look like healthy cells when viewed under a microscope.

The doctor compares the cancerous tissue with healthy tissue. Healthy tissue usually contains many different types of cells grouped together. If the cancerous tissue looks similar to healthy tissue and has different cell groupings, it is called “differentiated” or a “low-grade tumor.” If the cancerous tissue looks very different from healthy tissue, it is called “poorly differentiated” or a “high-grade tumor.” The cancer’s grade may help the doctor predict how quickly the cancer will spread. In general, the lower the tumor’s grade, the better the prognosis.

After a biopsy or when the tumor is surgically removed, doctors may look at the types of cells that are in the tumor. This is called histopathology. Three types of histopathology patterns may be present in the tumor:

  • Spindle cell melanoma (the cells are longer and tapered at the ends)

  • Epithelioid melanoma (the cells are oval-shaped)

  • Mixed cell melanoma (both spindle and epithelioid)

Generally, a tumor made up of spindle cells has a better prognosis than a tumor made up of epithelioid cells. The tumor is given a grade to describe the composition of its cells. A lower grade generally indicates a better prognosis than a higher grade.

GX: Grade cannot be evaluated

G1: A spindle cell melanoma

G2: A mixed cell melanoma

G3: An epithelioid melanoma

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Stage groups for eye melanoma

Doctors combine the T, N, M, and G information to say what stage the cancer is.

Stage I: The tumor is size category 1 and does not involve the ciliary body or other parts of the eye, nor has it spread to the regional lymph nodes or to other areas of the body (T1a, N0, M0).

Stage IIA: The tumor is a size category 1 that may or may not involve the ciliary body, with or without extraocular extension. Or, it is a size category 2 that does not involve the ciliary body. There is no spread to the regional lymph nodes or to other areas of the body (T1b, T1c, T1d, or T2a; N0, M0).

Stage IIB: The tumor is a size category 2 that involves the ciliary body but has not spread beyond the eyeball. Or, it is a size category 3 that has not spread to the ciliary body or eyeball. It has not spread to the regional lymph nodes or to other areas of the body (T2b or T3a; N0, M0).

Stage IIIA: Stage IIIA describes any one of these conditions:

  • A tumor of size category 2 with extraocular spread to a diameter of 5 mm or less, with or without ciliary body involvement, that has not spread to the lymph nodes or to other parts of the body (T2c or T2d, N0, M0).

  • A tumor of size category 3 that may or may not involve the ciliary body, with or without extraocular spread to a diameter of 5 mm or less, and has not spread to the lymph nodes or to other parts of the body (T3b or T3c, N0, M0).

  • A tumor of size category 4 that does not involve the ciliary body and has not spread to the lymph nodes or to other parts of the body (T4a, N0. M0).

Stage IIIB: Stage IIIB describes any one of these conditions:

  • The tumor is a size category 3 with ciliary body involvement and extraocular spread that has not spread to the lymph nodes or to other parts of the body (T3d, N0, M0).

  • The tumor is a size category 4 with or without ciliary body involvement that may or may not have spread outside the eyeball. It has not spread to the regional lymph nodes or to other areas of the body (T4b or T4c, N0, M0).

Stage IIIC: The tumor is a size category 4 that involves the ciliary body and has spread outside the eyeball. However, it has not spread to the regional lymph nodes or to other areas of the body (T4d or T4e; N0, M0).

Stage IV: This stage describes a tumor of any size that has spread to the lymph nodes and/or to other parts of the body outside of the eye (any T, N1, M0; or, any T, any N, M1).

Recurrent: Recurrent cancer is cancer that has come back after treatment. If the cancer does return, there will be another round of tests to learn about the extent of the recurrence. These tests and scans are often similar to those done at the time of the original diagnosis.

Used with permission of the American College of Surgeons, Chicago, Illinois. The original and primary source for this information is the AJCC Cancer Staging Manual, Eighth Edition (2017), published by Springer International Publishing.

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COMS tumor classifications

Instead of describing using the TNM system, uveal melanoma can also be classified by these guidelines from the Collaborative Ocular Melanoma Study (COMS).

  • Small: 1 mm to 3 mm in height and 5 mm to 16 mm in diameter

  • Medium: 3.1 mm to 8 mm in height and not more than 16 mm in diameter

  • Large: More than 8 mm in height and more than 16 mm in diameter

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Information about the cancer’s stage will help the doctor recommend a specific treatment plan. The next section in this guide is Types of Treatment. Use the menu to choose a different section to read in this guide.