Intraocular
Extraocular
Reese-Ellsworth Classification for Intraocular Tumors

Although there are several staging systems currently available for retinoblastoma, for the purpose of treatment, retinoblastoma is categorized into intraocular and extraocular disease.

5-year disease-free survival: >90%

Intraocular retinoblastoma is localized to the eye and may be confined to the retina or may extend to involve the globe; however, it does not extend beyond the eye into the tissues around the eye or to other parts of the body.

5-year disease-free survival: <10%

Extraocular retinoblastoma has extended beyond the eye. It may be confined to the tissues around the eye, or it may have spread, typically to the central nervous system or most commonly to the bone marrow or lymph nodes.

Reese and Ellsworth have developed a generally adopted classification system for intraocular retinoblastoma that has been shown to have prognostic significance for maintenance of sight and control of local disease at a time when surgery and external-beam radiation therapy (EBRT) were the only treatment options. The Reese-Ellsworth system is relevant to decisions regarding the use of local treatment modalities and chemoreduction, but another system has since evolved which may offer greater precision in stratifying risk for newer therapies. (See International Classification System in the Future Directions ¹ section of this summary.)

Group I: very favorable for maintenance of sight

1. Solitary tumor, smaller than 4 disc diameters (DD), at or behind the equator.
2. Multiple tumors, none larger than 4 DD, all at or behind the equator.

Group II: favorable for maintenance of sight

1. Solitary tumor, 4 to 10 DD at or behind the equator.
2. Multiple tumors, 4 to 10 DD behind the equator.

Group III: possible for maintenance of sight

1. Any lesion anterior to the equator.
2. Solitary tumor, larger than 10 DD behind the equator.

Group IV: unfavorable for maintenance of sight

1. Multiple tumors, some larger than 10 DD.
2. Any lesion extending anteriorly to the ora serrata.

Group V: very unfavorable for maintenance of sight

1. Massive tumors involving more than one half the retina.
2. Vitreous seeding.

There is now a new classification system for retinoblastoma. The International Classification for Intraocular Retinoblastoma that is used in the current Children’s Oncology Group treatment studies, as well in some institutional studies, has been shown to assist in predicting those who are likely to be cured without the need for enucleation or EBRT.[1-3]

International Classification System for Intraocular Retinoblastoma

• Group A: Small intraretinal tumors away from foveola and disc.
  • All tumors are 3 mm or smaller in greatest dimension, confined to the retina and
  • All tumors are located further than 3 mm from the foveola and 1.5 mm from the optic disc.



• Group B: All remaining discrete tumors confined to the retina.
  • All other tumors confined to the retina not in Group A.
  • Tumor-associated subretinal fluid less than 3 mm from the tumor with no subretinal seeding.



• Group C: Discrete local disease with minimal subretinal or vitreous seeding.
  • Tumor(s) are discrete.
  • Subretinal fluid, present or past, without seeding involving up to one-fourth of the retina.
  • Local fine vitreous seeding may be present close to discrete tumor.
  • Local subretinal seeding less than 3 mm (2 DD) from the tumor.



• Group D: Diffuse disease with significant vitreous or subretinal seeding.
  • Tumor(s) may be massive or diffuse.
  • Subretinal fluid present or past without seeding, involving up to total retinal detachment.
  • Diffuse or massive vitreous disease may include “greasy” seeds or avascular tumor masses.
  • Diffuse subretinal seeding may include subretinal plaques or tumor nodules.



• Group E: Presence of any one or more of these poor prognosis features.
  • Tumor touching the lens.
  • Tumor anterior to anterior vitreous face involving ciliary body or anterior segment.
  • Diffuse infiltrating retinoblastoma.
  • Neovascular glaucoma.
  • Opaque media from hemorrhage.
  • Tumor necrosis with aseptic orbital cellulites.
  • Phthisis bulbi.

References

1. Murphree L: Staging and grouping of retinoblastoma. In: Singh A, Damato B: Clinical Ophthalmic Oncology. Philadelphia, Pa: Saunders Elsevier, 2007, pp 422-7. 
   
   
2. Zage PE, Reitman AJ, Seshadri R, et al.: Outcomes of a two-drug chemotherapy regimen for intraocular retinoblastoma. Pediatr Blood Cancer 50 (3): 567-72, 2008.  [PUBMED Abstract]
   
   
3. Shields CL, Mashayekhi A, Au AK, et al.: The International Classification of Retinoblastoma predicts chemoreduction success. Ophthalmology 113 (12): 2276-80, 2006.  [PUBMED Abstract]