Eye Cancer Stages

After someone is diagnosed with eye cancer, doctors will try to figure out if it has spread, and if so, how far. This process is called staging. The stage of a 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 the stage determined?

The cancer stage is determined from the results of eye exams, imaging tests (ultrasound, CT or MRI scan, etc.) and other tests. (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 system described below is the most recent AJCC system, effective January 2018.

The TNM system is based on 3 key pieces of information:

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

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 5 millimeters (mm) — about 1/5 of an inch — or less across.
• T4b: The part of the tumor that is outside the eyeball is greater than 5 mm (about 1/5 of an inch) across.

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 T1-size tumor is not growing into the ciliary body or growing outside the eyeball.
• T1b: The T1-size tumor is growing into the ciliary body.
• T1c: The T1-size tumor is not growing into the ciliary body but is growing outside of the eyeball. The part of the tumor that is outside the eyeball is 5 mm (about 1/5 of an inch) or less across.
• T1d: The T1-size tumor is growing into the ciliary body and also outside of the eyeball. The part of the tumor that is outside the eyeball is 5 mm (about 1/5 of an inch) or less across.

T2 tumors:

• T2a: The T2-size tumor is not growing into the ciliary body or growing outside the eyeball.
• T2b: The T2-size tumor is growing into the ciliary body.
• T2c: The T2-size tumor is not growing into the ciliary body but is growing outside the eyeball. The part of the tumor that is outside the eyeball is 5 mm (about 1/5 of an inch) or less across.
• T2d: The T2-size tumor is growing into the ciliary body and also outside the eyeball. The part of the tumor that is outside the eyeball is 5 mm (about 1/5 of an inch) or less across.

T3 tumors:

• T3a: The T3-size tumor is not growing into the ciliary body and is not growing outside the eyeball.
• T3b: The T3-size tumor is growing into the ciliary body.
• T3c: The T3-size tumor is not growing into the ciliary body but is growing outside the eyeball. The part of the tumor that is outside the eyeball is 5 mm (about 1/5 of an inch) or less across.
• T3d: The T3-size tumor is growing into the ciliary body and also outside the eyeball. The part of the tumor that is outside the eyeball is 5 mm (about 1/5 of an inch) or less across.

T4 tumors:

• T4a: The T4-size tumor is not growing into the ciliary body or growing outside the eyeball.
• T4b: The T4-size tumor is growing into the ciliary body.
• T4c: The T4-size tumor is not growing into the ciliary body but is growing outside the eyeball. The part of the tumor that is outside the eyeball is 5 mm (about 1/5 of an inch) or less across.
• T4d: The T4-size tumor is growing into the ciliary body and also outside the eyeball. The part of the tumor that is outside the eyeball is 5 mm (about 1/5 of an inch) or less 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 greater than 5 mm across.

N categories for iris, ciliary body, and choroidal melanomas

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

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. If you’re interested in learning more about it and how it might apply to your cancer, ask your doctor to explain it to you in a way you understand.

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

The TNM system is very detailed, but in practice doctors may use the simpler staging system devised by the COMS group, which has done most of the clinical research on how to treat intraocular melanoma. This system 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