Eye Cancer Stages

Most eye cancers are melanomas (also known as ocular melanomas or intraocular melanomas). After someone is diagnosed with eye cancer, doctors will try to figure out how big it is, how far it has grown into nearby structures, and if it has spread. This process is called staging.

The stage of an eye cancer describes how much cancer is in the body. It helps determine how serious the cancer is and how best to treat it. Doctors also use a cancer's stage when talking about survival statistics.

How is eye cancer stage determined?

The cancer stage is based on the results of eye exams, imaging tests (ultrasound, CT or MRI scan, etc.), and any other tests that are done. (See Tests for Eye Cancer.)

A staging system is a standard way for the cancer care team to describe how far a cancer has spread. The most common systems used to describe the stages of eye melanomas are the American Joint Committee on Cancer (AJCC) TNM system and the system used by the Collaborative Ocular Melanoma Study (COMS) group.

AJCC TNM staging system for melanoma of the eye

Most eye melanomas start in the uvea, which includes the iris, ciliary body, and choroid. (See What Is Eye Cancer?) The system below is for these uveal melanomas.

Less often, melanomas can start in other areas in or around the eye, some of which have their own staging systems (such as conjunctival melanoma). Talk to your doctor to learn more about your stage if you have a less common type of eye melanoma.

The AJCC TNM system for uveal melanoma is based on 3 key pieces of information:

• The size and extent of the main (primary) tumor (T): How large is the eye tumor? Has it invaded into nearby structures?
• The spread to nearby lymph nodes (N): Has the cancer spread to the nearby lymph nodes around the ear or neck? Has the cancer spread to (not grown into) other parts of the eye?
• The spread (metastasis) to distant sites (M): Has the cancer spread to distant parts of the body? (The most common site of spread is the liver.)

Numbers or letters appear after T, N, and M to provide more details about each of these factors. Higher numbers or letters mean the cancer is more advanced.

The T categories for ciliary body and choroidal melanomas are different from the T categories for iris melanomas. But the N and M categories are the same for melanomas in all 3 parts of the uvea.

T categories for ciliary body and choroidal melanoma

Ciliary body and choroidal melanomas are divided into 4 main T categories (T1 to T4), based on the diameter (width) and the thickness of the tumor. T1 tumors are the smallest; T4 tumors are the largest. Each of these categories is then broken down further, based on how far the tumor has grown.

TX: The primary tumor cannot be assessed; information not known.

T0: No evidence of a primary tumor.

T1 tumors:

• T1a: The tumor is size category 1, and it is not growing into the ciliary body or outside the eyeball.
• T1b: The tumor is size category 1, and it is growing into the ciliary body.
• T1c: The tumor is size category 1, and it is not growing into the ciliary body but is growing outside the eyeball. The part of the tumor that is outside the eyeball is no more than 5 mm (about 1/5 of an inch) across.
• T1d: The tumor is size category 1, and it is growing into the ciliary body and also outside of the eyeball. The part of the tumor that is outside the eyeball is no more than 5 mm (about 1/5 of an inch) across.

T2 tumors:

• T2a: The tumor is size category 2, and it is not growing into the ciliary body or outside the eyeball.
• T2b: The tumor is size category 2, and it is growing into the ciliary body.
• T2c: The tumor is size category 2, and it is not growing into the ciliary body but is growing outside the eyeball. The part of the tumor that is outside the eyeball is no more than 5 mm (about 1/5 of an inch) across.
• T2d: The tumor is size category 2, and it is growing into the ciliary body and also outside the eyeball. The part of the tumor that is outside the eyeball is no more than 5 mm (about 1/5 of an inch) across.

T3 tumors:

• T3a: The tumor is size category 3, and it is not growing into the ciliary body or growing outside the eyeball.
• T3b: The tumor is size category 3, and it is growing into the ciliary body.
• T3c: The tumor is size category 3, and it is not growing into the ciliary body but is growing outside the eyeball. The part of the tumor that is outside the eyeball is no more than 5 mm (about 1/5 of an inch) across.
• T3d: The tumor is size category 3, and it is growing into the ciliary body and also outside the eyeball. The part of the tumor that is outside the eyeball is no more than 5 mm (about 1/5 of an inch) across.

T4 tumors:

• T4a: The tumor is size category 4, and it is not growing into the ciliary body or outside the eyeball.
• T4b: The tumor is size category 4, and it is growing into the ciliary body.
• T4c: The tumor is size category 4, and it is not growing into the ciliary body but is growing outside the eyeball. The part of the tumor that is outside the eyeball is no more than 5 mm (about 1/5 of an inch) across.
• T4d: The tumor is size category 4, and it is growing into the ciliary body and also outside the eyeball. The part of the tumor that is outside the eyeball is no more than 5 mm (about 1/5 of an inch) across.
• T4e: The tumor can be any size. It is growing outside the eyeball, and the part of the tumor that is outside the eyeball is more than 5 mm across.

T categories for iris melanoma

TX: The primary tumor cannot be assessed; information not known.

T0: No evidence of a primary tumor.

T1: Tumor is only in the iris.

• T1a: The tumor is only in the iris and touches 1/4 or less of the iris.
• T1b: The tumor is only in the iris and touches more than 1/4 of the iris.
• T1c: The tumor is only in the iris and is causing an increase in the eye pressure (glaucoma).

T2: Tumor has grown into the ciliary body or choroid (or both).

• T2a: Tumor has grown into the ciliary body.
• T2b: Tumor has grown into the ciliary body and choroid.
• T2c: Tumor has grown into the ciliary body, choroid, or both, and it is causing glaucoma.

T3: Tumor has grown into the ciliary body and/or choroid and into the sclera.

T4: Tumor extends outside the eyeball.

• T4a: The part of the tumor that is outside the eyeball is no more than 5 mm — about 1/5 of an inch — across.
• T4b: The part of the tumor that is outside the eyeball is more than 5 mm across.

N categories for iris, ciliary body, and choroidal melanomas

The N categories are the same for melanomas of the iris, ciliary body, and choroid.

NX: Lymph nodes cannot be assessed.

N0: Cancer has not spread to nearby lymph nodes.

N1: Cancer has spread to nearby lymph nodes, or it has spread as small cancer deposits in other parts of the eye.

• N1a: Cancer has spread to nearby lymph nodes.
• N1b: Cancer has not spread to nearby lymph nodes, but it has spread as small cancer deposits in other parts of the eye.

M categories for iris, ciliary body, and choroidal melanomas

The M categories are the same for iris, ciliary body, and choroidal melanoma.

M0: Cancer has not spread to distant parts of the body.

M1: Cancer has spread to distant parts of the body.

• M1a: The largest area of cancer spread is no more than 3 centimeters (cm) — a little over an inch — across.
• M1b: The largest area of cancer spread is between 3.1 and 8 cm across (8 cm is a little over 3 inches).
• M1c: The largest area of cancer spread is 8.1 cm or more across.

Stage grouping

To assign an overall stage, the T, N, and M categories are combined in a process called stage grouping. The stages are described by Roman numerals from I (the least advanced) to IV (the most advanced). Some stages are further divided with letters.

Stage	TNM categories
Stage I	T1a, N0, M0
Stage IIA	T1b to T1d, N0, M0 or T2a, N0, M0
Stage IIB	T2b or T3a, N0, M0
Stage IIIA	T2c or T2d, N0, M0 or T3b or T3c, N0, M0 or T4a, N0, M0
Stage IIIB	T3d, N0, M0 or T4b or T4c, N0, M0
Stage IIIC	T4d or T4e, N0, M0
Stage IV	Any T, N1, M0 or Any T, any N, M1

This staging system for uveal melanoma can be very complex. To learn more about it and how it might apply to your cancer, ask your doctor to explain it to you in a way you understand.

Grade (G) and histopathology

Doctors might also describe eye melanoma by its grade (G). The grade describes how abnormal the cancer cells look under a microscope.

• If the cancerous tissue looks a lot like healthy tissue, it is called “differentiated” or “low grade.”
• If the cancerous tissue looks very different from healthy tissue, it is called “poorly differentiated” or high grade.”

The grade is not used to help determine the stage of the cancer, but it may help the doctor predict how likely it is that the cancer will spread. In general, the lower the tumor’s grade, the better the outlook.

After a biopsy or surgery to remove the tumor, doctors may look at the types of cells in the tumor. This is called its histopathology. Three main types of histopathology patterns may be seen:

• Spindle cell melanoma (the cells are longer and tapered at the ends)
• Epithelioid melanoma (the cells are oval-shaped)
• Mixed cell melanoma (the tumor contains both spindle and epithelioid cells)

Generally, a tumor made up of only (or mostly) spindle cells tends to have a better outlook (prognosis) and is given a lower grade.

• GX: Grade cannot be assessed
• G1: A spindle cell melanoma
• G2: A mixed cell melanoma
• G3: An epithelioid melanoma

Collaborative Ocular Melanoma Study (COMS) staging of melanoma of the eye

The TNM system is very detailed, but when deciding on treatment doctors may use the simpler system devised by the COMS group, which has done most of the clinical research on how to treat intraocular melanoma. This system is only based on tumor size. It divides eye melanomas into small, medium, and large:

• Small: Between 1 mm and 3 mm in height and between 5 mm and 16 mm across
• Medium: Between 3.1 mm and 8 mm in height and no more than 16 mm across
• Large: More than 8 mm in height or more than 16 mm across