Stages of eye cancer

The stage of a cancer tells you how big it is and how far it’s spread. It helps your doctor decide which treatment you need.

It is important because the stage often decides the treatment. The tests and scans you have to diagnose cancer give some information about the stage. But your doctor may not be able to tell you the exact stage until you have surgery.

TNM Staging

Doctors use different systems to stage eye cancer. One of these is the TNM staging system and is very detailed. TNM stands for Tumour, Node, Metastasis.

T - Tumour 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.

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

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

There are different types of eye cancer. The node and metastases stage are generally the same for the different types. But the tumour stages can be different, depending on the type of eye cancer. 

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 (COMS) staging. 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 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.

Stages of lymphoma of the eye

Lymphomas that start in the tissue surrounding the eyes use a TNM staging system developed for this type of cancer. For example, there is a separate staging for lymphomas of the eyelids or conjunctiva called ocular adnexal Lymphomas.

There are other lymphomas of the eye called intraocular lymphomas. They use the same staging system as Non-Hodgkin lymphomas elsewhere in the body. 

Staging for other types of eye cancer

Most types of eye cancer use the TNM staging system. But the TNM stages are slightly different depending on the type. For example, there are different TNM staging systems for:

• melanoma of the conjunctiva
• lacrimal gland cancer
• retinoblastoma
• squamous cell cancer of the eye

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.