Stages of eye cancer

The stage of a cancer tells you how big it is and how far it has spread. It helps your doctor decide the best treatment for you.

Doctors use different systems to stage eye cancer. The TNM staging system is one of the most common ways to stage the different types of eye cancer. TNM stands for Tumour, Node and Metastasis.

Doctors may also use a simpler staging system for uveal melanoma based on the Collaborative Ocular Melanoma Study (COMS).

Your doctor may not be able to tell you the exact stage until you have surgery.

TNM Staging

The TNM staging system is one of the most common ways to stage the different types of eye cancer. TNM stands for Tumour, Node and Metastasis.

Tumour (T)

T describes the size of the tumour, which part of the eye it is in and whether it has spread into other areas of the eye or outside of the eye.

Node (N)

N describes whether the cancer has spread to the lymph nodes. The lymph nodes are part of the lymphatic system that helps to fight infection.

Metastasis (M)

M describes whether the cancer has spread to a different part of the body.

The tumour stages can be different, depending on the type of eye cancer, but the node and metastasis stages are generally the same for the different types.

TNM staging of uveal melanoma

Uveal melanoma is the most common type of eye cancer in adults. The uvea is the middle layer of the eye and is made up of the choroid, iris and ciliary body. 

There are different tumour stages for:

• melanoma of the iris
• melanoma of ciliary body and choroid

Your eye specialist can explain what your TNM stage is and what this means for you. They use information from the American Joint Committee on cancer (AJCC) staging system.

Simple stages of uveal melanoma

Doctors also use a simpler staging system for uveal melanoma based on the Collaborative Ocular Melanoma Study (COMS). It uses the terms small, medium and large which is based on the thickness and width of the tumour. 

• small – the melanoma is no more than 2.4 mm thick, and less than 16 mm wide

• medium – the melanoma is between 2.5 and 10 mm thick, and less than 16 mm wide

• large – the melanoma is more than 10 mm thick or more than 16 mm wide

Some specialists use the term advanced or metastatic cancer if the cancer has grown into tissues around the eye or another part of the body, such as the liver.

If your cancer has grown into the tissues around the eye, it is called extraocular extension.  

Recurrent melanoma of the eye means a melanoma that has come back after it was first treated. It may have come back in your eye or another part of your body.

Staging of lymphoma of the eye

Doctors use the TNM staging system for lymphomas that start in the tissue surrounding the eyes. These are lymphomas of the eyelids or conjunctiva called ocular adnexal lymphomas.

But, for other lymphomas of the eye called intraocular lymphomas, they use the same staging system as for Non-Hodgkin lymphomas elsewhere in the body.

Staging for other types of eye cancer

The TNM stages are slightly different depending on the type of eye cancer. There are different TNM staging systems for:

• melanoma of the conjunctiva

• lacrimal gland cancer

• eyelid cancer, including squamous cell and basal cell cancer

• sarcoma of the eye

• retinoblastoma

Each TNM stage is quite detailed and complicated. Your eye specialist will explain the stage of your cancer and what this means for you. Ask questions if you’re not sure about anything.