Group
Subgroup
Descriptor
Prognosis
Group I
Ia
Solitary tumor < 4 DD at or behind the equator
Very favorable
Ib
Multiple tumors, none > 4 DD, all at or behind the equator
Group II
IIa
Solitary tumor, 4–10 DD, all at or behind the equator
Favorable
IIb
Multiple tumors, 4–10 DD, behind the equator
Group III
IIIa
Any lesion anterior to the equator
Doubtful
IIIb
Solitary tumors larger than 10 DD behind the equator
Group IV
IVa
Multiple tumors, some larger than 10 DD
Unfavorable
IVb
Any lesion extending anteriorly to the ora serrata
Group V
Va
Massive tumors involving over half the retina
Very unfavorable
Vb
Vitreous seeding
The historical absence of a staging system also reflects the low incidence of extraocular disease in developed countries. Until relatively recently, the fact that extraocular disease is still a clinical issue in developing countries was largely overlooked in publications about retinoblastoma from the Northern Hemisphere. An international perspective on retinoblastoma is presented in Chap. 5.
3.4 First International Classification of Retinoblastoma
In this chapter we present the first international classification system for retinoblastoma. It consists of both presurgical grouping to help the ophthalmologist assess the risk of the disease and its treatment to the child’s eye[s] and vision and a staging schema for assessment of the risk the disease poses to the child’s life and well-being (Table 3.2). The organization and content of both the grouping and the staging were developed with unprecedented international cooperation among oncologists and ophthalmologists who treat this disease. The fact that four new cooperative group clinical trials, the first in almost 40 years, have recently opened to assess the management of retinoblastoma gives some testimony to the role of reality-based tumor classification systems (Chap. 21). All of the four new clinical trials use the international grouping and staging of retinoblastoma described in this chapter.
Table 3.2
Clinical and investigational aspects of staging and grouping in the international retinoblastoma classification
|
Aspect |
Staging |
Grouping |
|---|---|---|
|
Focus |
Patient and tumor |
Eye |
|
Primary specialist |
Oncologist and pathologist |
Ocular oncologist |
|
Relation to tumor excision/biopsy |
Clinical staging (presurgical) |
Presurgical |
|
Pathologic staging (postsurgical) | ||
|
Outcome measure |
Survival of the patient |
Survival of the eye/vision |
|
Information required |
Has one eye been enucleated? |
Results of the grouping EUA |
|
Is tumor confined to the eye? |
Is there tumor in one or both eyes? | |
|
Is there microscopic orbital disease? |
Is the tumor confined to the retina? | |
|
Has the tumor grossly invaded regional structures? |
Is significant retinal detachment present? | |
|
Have metastases occurred? |
Are vitreous and/or subretinal seeding present? | |
|
Number of metastatic foci? |
Has/have the functional and/or structural integrity of the eye(s) been destroyed? | |
|
Is there CNS disease? | ||
|
Sources of information |
Medical record including all diagnostic imaging studies and the tumor pathology report |
Functional vision, ophthalmic examination, ocular ultrasound (CT rarely necessary) |
|
Designator |
Roman numerals |
Capital letters A–E |
|
Subgroups |
Yes |
No |
|
Used in COG clinical trials |
Yes |
Yes |
|
Time from study entry to: |
Event-free survival (EFS) |
Event-free ocular survival (EFOS) |
|
Disease recurrence requiring off-protocol therapy | ||
|
Loss to follow-up |
3.5 Staging the Patient
3.5.1 Background
Retinoblastoma differs from other pediatric neoplasms in never having had a widely accepted classification system that encompasses the entire spectrum of the disease. The clinical scenario of a patient being treated for intraocular disease where survival is not in significant jeopardy is completely different from the case with metastatic disease in which there is a life-threatening extraocular disease.
The absence of a widely accepted staging system in the recent past made it extremely difficult to design studies or to compare the outcomes from published studies that evaluated disease extension, risk factors for metastatic disease, and/or response to therapy.
3.5.2 Other Staging Systems
There are at least five published reports that included a staging classification; however, none has been widely adopted [5–9].
3.5.2.1 St. Jude’s Hospital Staging and TNM System
Some classifications, like the St. Jude’s and TNM system, embraced the whole spectrum of retinoblastoma and included ophthalmologic data, and the TNM has been recently updated but was seldom used by ophthalmologists for clinical grouping who preferred the Reese-Ellsworth group classification and more recently the international classification [3, 4, 10].
3.5.2.2 Children’s Cooperative Group Classification
Other classifications, such as the CCG, considered only extraocular disease omitting important pathological features, like choroidal or postlaminar optic nerve invasion [7].
3.5.2.3 Grabowski-Abramson Classification
The Grabowski-Abramson classification, later modified by Abramson, was also used by some groups [8]. In that classification, patients with CNS invasion were categorized as Stage III and those with systemic metastases as Stage IV. The current clinical experience is that patients with Grabowski-Abramson Stage III are seldom curable, while those with Stage IV can often be rescued with high-dose chemotherapy and bone marrow rescue.
3.5.3 International Retinoblastoma Classification: Staging System [11]
At the International Symposium on Retinoblastoma held in Paris in May 2003, a committee of retinoblastoma experts from large centers worldwide drafted yet another staging system. Investigators from centers in South America and North America, Europe, and South Africa edited this draft into a consensus document. This staging system was designed to be used in conjunction with the new intraocular grouping system that was also under development at the same time. This staging system combines clinical and pathologic staging and has a single end point—survival of the patient with retinoblastoma. Patients are classified according to extent of disease including the presence of microscopic or overt extraocular extension and metastatic extension (Table 3.3). Roman numerals are used for stage assignment. This staging system has been recently validated in a large cohort of patients [12].
Table 3.3
Staging system for patients in international retinoblastoma classification
|
Stage |
Substage |
Descriptor |
Comments | |
|---|---|---|---|---|
|
Stage 0 |
Intraocular tumor only |
No evidence of regional or metastatic disease; patient may not have had an enucleation | ||
|
Stage I |
Tumor completely removed by enucleation |
Retinoblastoma may be present in the non-enucleated eye. High-risk pathology may be present within the enucleated specimen | ||
|
Stage II |
Residual orbital tumor |
Microscopic tumor present in the optic nerve at the site of surgical resection (cut end of nerve) | ||
|
Stage III |
(a) Overt orbital extension |
Overt regional disease |
Orbital or node involvement diagnosed clinically or by neuroimaging | |
|
(b) Preauricular or cervical lymph node extension | ||||
|
Stage IV |
(a) Hematogenous metastasis without CNS disease |
1. Single lesion |
Metastatic disease |
|
|
2. Multiple lesions | ||||
|
(b) CNS disease |
1. Prechiasmatic lesion | |||
|
2. CNS mass | ||||
|
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