Staging is the process of finding out where and how much a cancer has spread. The outlook (prognosis) for people with cancer depends, to a large extent, on the cancer's stage. The stage of a cancer is one of the most important factors in choosing treatment.

Retinoblastoma is staged based on the results of eye exams, imaging tests, and any biopsies that were done. These tests were described in the section "How is retinoblastoma diagnosed?"

A staging system is a standardized way for your child's cancer care team to summarize information about how far a cancer has spread. Doctors use a staging system to predict the outlook for saving the child's vision, as well as for survival and the likelihood that certain treatments will be effective.

Several detailed systems can be used to stage retinoblastoma. For practical purposes, when determining the best treatment options, doctors often divide retinoblastomas into 3 main groups:

• intraocular: it is still within the eye
• orbital: it has spread to the eye socket
• metastatic: it has spread to distant parts of the body

The 2 systems described below are used only for intraocular retinoblastomas.

The Reese-Ellsworth staging system

Doctors often use the Reese-Ellsworth staging system to classify retinoblastomas that have not spread beyond the eye (intraocular retinoblastomas). This helps determine the likelihood of preserving vision while still effectively treating the tumor.

This system was developed in the 1960s, when most children were being treated with external beam radiation therapy (EBRT). The terms favorable, doubtful, unfavorable, etc. in this staging system refer to the likelihood that the cancer can be treated effectively while preserving the affected eye. These terms do not refer to the likelihood of the child's survival. Indeed, more than 90% of children with intraocular retinoblastomas are cured. The major challenge is saving their sight.

To explain the groupings below, it will help to define a couple of terms. The optic disk is the end of the optic nerve where it is attached to the retina. Because retinoblastomas are diagnosed by looking at the retina through an ophthalmoscope, doctors cannot measure their size directly using a ruler. Instead they compare the size of the tumor with the size of the optic disk, which is usually about 1.5 millimeters (1/16 inch) across. For example, a tumor estimated to be 3 times the size of the disk (3 disk diameters or 3 DD) would be about 4.5 millimeters (3/16 inch) across.

The equator is an imaginary line that divides the front and back halves of the eyeball.

The Reese-Ellsworth staging system divides intraocular retinoblastoma into 5 groups. The higher the group number, from 1 to 5, the lower the chance of controlling the retinoblastoma or of saving the eye or any useful vision.

Group 1 (very favorable for saving [or preserving] the eye)

• one tumor, smaller than 4 disc diameters (DD), at or behind the equator
• multiple tumors smaller than 4 DD, all at or behind the equator

Group 2 (favorable for saving [or preserving] the eye)

• one tumor, 4 to 10 DD , at or behind the equator
• multiple tumors, 4 to 10 DD, all at or behind the equator

Group 3 (doubtful for saving [or preserving] the eye)

• any tumor in front of the equator
• one tumor, larger than 10 DD, behind the equator

Group 4 (unfavorable for saving [or preserving] the eye)

• multiple tumors, some larger than 10 DD
• any tumor extending anteriorly (toward the front of the eye) to the ora serrata (front edge of the retina)

Group 5 (very unfavorable for saving [or preserving] the eye)

• tumors involving more than half of the retina
• vitreous seeding (spread of tumors into the gelatinous material that fills the eye)

Although this staging system was first designed to determine how useful radiation therapy might be in a given patient, it still provides some useful information about which current treatments might be most effective. For example:

A group 1 retinoblastoma can very likely be controlled with chemotherapy, photocoagulation, cryotherapy, thermotherapy, brachytherapy, or external beam radiation therapy while still preserving vision in the eye.

A group 4 or especially group 5 retinoblastoma is very unlikely to be controlled with chemotherapy or radiation therapy. Even if it were controlled, the vision in the eye would be very poor.

International Classification for Intraocular Retinoblastoma

The International Classification for Intraocular Retinoblastoma is a newer staging system, which takes into account what has been learned about the disease in recent decades. This system divides retinoblastomas into 5 groups, labeled A through E, based on the chances that the eye can be saved using current treatment options:

Group A

Small tumors (3 mm across or less) that are confined to the retina and are not near important structures such as the optic disk (where the optic nerve enters the retina) or the foveola (the center of the vision).

Group B

All other tumors (either larger than 3 mm or small but close to the optic disk or foveola) that are still confined to the retina.

Group C

Well-defined tumors with small amounts of spread under the retina (subretinal seeding) or into the gelatinous material that fills the eye (vitreous seeding).

Group D

Large or poorly defined tumors with widespread vitreous or subretinal seeding. The retina may have become detached from the back of the eye.

Group E

Tumor's large size, location, or other factors mean there is almost no chance the eye can be saved.

Other staging systems have also been developed and may be used by some doctors. Be sure to ask your child's doctor which system is being used.

It is important to know that regardless of the stage, almost all children with intraocular retinoblastoma can be cured if they are properly treated.

Last Medical Review: 10/26/2009
Last Revised: 10/26/2009