Eye Cancer Stages: How Uveal Melanoma, Retinoblastoma and Other Eye Tumors Are Staged

Eye cancer stages describe how large a tumor is and how far it has spread, and each type of eye cancer uses its own system: COMS size and AJCC stage for uveal melanoma, groups A to E and an AJCC stage for retinoblastoma, and AJCC categories for cancers of the conjunctiva and eyelid. This article explains each in plain language, using the 8th edition of the AJCC (American Joint Committee on Cancer) system cited in the sources below; reports from other years may differ slightly.

What do eye cancer stages mean?

Most cancers are staged with the TNM framework: T describes the main tumor's size and invasion of nearby structures, N spread to lymph nodes (for eye cancers, usually in front of the ear, under the jaw or in the neck), and M spread to distant organs. These are combined into stage groups, usually I to IV. Staging is based on examination and imaging (clinical stage, marked "c") and, when tissue is removed, on pathology (marked "p").

How is uveal melanoma staged?

The COMS size categories, from the Collaborative Ocular Melanoma Study, classify melanomas of the choroid by height (thickness) and largest base diameter. The table uses the definitions of the COMS medium-tumor trial and most current reports; the original version set the height boundaries at 3 mm and 8 mm.

The AJCC system uses a grid of thickness and base diameter to assign one of four size categories: T1 covers the smallest tumors (for example, up to about 12 mm across and 3 mm thick) and T4 the largest (such as more than 18 mm across or more than 15 mm thick). Each category is refined if the tumor involves the ciliary body or has grown through the eye wall, both of which signal a higher risk. With the N and M categories, this gives stages I to IV, the highest being used when the cancer has spread to lymph nodes or distant organs. Iris melanoma has separate categories based on how many clock hours of the iris are involved, whether glaucoma is present and whether the tumor extends beyond the iris.

What it means for you: size is closely linked to outcome. In published series, the 5-year risk of metastasis was about 6% for tumors up to 3 mm thick, 14% for 3.1–8 mm and 35% above 8 mm. Size and position also guide treatment, from observation or a plaque for small tumors to protons or removal of the eye for large ones, and tumor genetic testing adds information that stage alone cannot give.

How is retinoblastoma staged?

Retinoblastoma, the eye cancer of young children, is classified in two complementary ways. The international groups A to E describe the disease inside the eye and predict how likely the eye is to be saved. Two slightly different versions exist; this summary follows their common core:

The AJCC stage adds spread outside the eye and heredity. cT1 and cT2 describe tumors inside the eye with increasing fluid or seeding; cT3 advanced changes such as invasion of the iris or ciliary body, raised pressure or heavy bleeding; cT4 spread along the optic nerve or into the orbit; N1 and M1 spread to lymph nodes or distant sites. It was the first cancer staging system to include heredity: H1 means bilateral disease, trilateral retinoblastoma (with a related brain tumor), a family history or a proven inherited RB1 change; H0 means normal RB1 genes on a sensitive test, and HX unknown.

Stage matters for survival as well as for the eye: in a global study of 4,064 children from 149 countries, those with cT4 disease had almost nine times the risk of death of those with cT1 disease. See intra-arterial and intravitreal chemotherapy and retinoblastoma genetics.

How are conjunctival cancers staged?

Cancers of the conjunctiva, the thin membrane covering the white of the eye, are staged by size, location and invasion. For conjunctival carcinoma (ocular surface squamous neoplasia):

In a study of 136 eyes staged this way, 83% of tumors were T3 at presentation and all recurrences (14% overall) occurred in T3 tumors.

For conjunctival melanoma, T1 means a tumor over the white of the eye, subdivided by the number of quadrants involved; T2 a tumor elsewhere, such as the inner eyelid or caruncle; T3 invasion of the eyeball, eyelid, orbit, tear drainage system or sinuses; and T4 spread to the brain. Pathology adds tumor thickness (2 mm or less, or more). In a study of 425 patients followed for a mean of about five years, melanoma-related death occurred in 4% of T1, 12% of T2 and 18% of T3 tumors. See also conjunctival tumors.

How are eyelid cancers staged?

Basal cell, squamous cell and sebaceous carcinomas of the eyelid share one AJCC system. T1 tumors measure 10 mm or less, T2 more than 10 mm and up to 20 mm, and T3 more than 20 mm and up to 30 mm; each is subdivided by depth ("a" spares the tarsal plate and lid margin, "b" invades them, "c" involves the full thickness of the lid). T4 tumors invade neighboring eye, orbital or facial structures, or bone, sinuses or the brain.

Eyelid melanoma and Merkel cell carcinoma use the skin cancer systems instead. See eyelid cancer.

What does the stage mean for treatment and outlook?

Smaller, localized tumors can usually be treated in ways that preserve the eye and vision, while advanced stages may need more extensive surgery, radiation or systemic treatment coordinated with oncology teams. Stage predicts outcome but is not the whole story: tumor genetics refine it in uveal melanoma, and heredity shapes follow-up for the family in retinoblastoma. Other eye tumors, such as lymphomas and metastases from cancers elsewhere, are staged according to the underlying cancer, and benign lesions such as a choroidal nevus are not staged at all.

If a report uses a stage you do not understand, a second opinion can help; see also is eye cancer curable?