peer reviewed
Advances in the Management of Retinoblastoma
CAROL L. SHIELDS, MD • JERRY
A. SHIELDS, MD
Retinoblastoma
represents approximately 4% of all pediatric malignancies and is the most common
intraocular malignancy in children.1,2
It is estimated that 300 new cases of retinoblastoma are diagnosed in the United
States each year and 5000 cases worldwide. Over 95% of children with retinoblastoma
in the United States and other medically developed nations survive their malignancy,
whereas about 50% survive worldwide.
LET'S REVIEW THE TERMINOLOGY FOR
RETINOBLASTOMA
Retinoblastoma can be classified in 3 different ways: familial
or sporadic, bilateral or unilateral, and heritable or nonheritable. About two-thirds
of all cases are unilateral and one-third are bilateral. Genetically, it is simpler
to discuss retinoblastoma with the latter classification of heritable (germline
mutation) or nonheritable (somatic mutation). Bilateral and familial retinoblastoma
are caused by a germline mutation and are thus heritable. Unilateral sporadic retinoblastoma
is usually not heritable, but approximately 15% of patients will show a germline
mutation. Genetic testing using DNA analysis of the patient's tumor and peripheral
blood can help identify those patients with germline mutation.
FIRST, REMEMBER THE LIFE THREATENING
ASPECTS OF RETINOBLASTOMA
Children with retinoblastoma are at risk for 3 important, life
threatening problems including metastasis from retinoblastoma, intracranial neuroblastic
malignancy (trilateral retinoblastoma), and second primary tumors.
Retinoblastoma metastasis typically develops within 1 year of
the diagnosis of the intraocular tumor. Those at greatest risk for metastasis show
features of retinoblastoma invasion beyond the lamina cribrosa in the optic nerve,
in the choroid, sclera, orbit, or anterior chamber.3
Patients with invasive retinoblastoma should be treated with chemotherapy for 4
to 6 months to prevent metastases.
Patient with hereditary retinoblastoma are at risk for neuroblastic
intracranial malignancy in the first 5 years of life, most often manifesting as
pinealoblastoma or other parasellar tumors.4
This has been termed "trilateral" retinoblastoma and is found in approximately 3%
of all children with retinoblastoma. Unfortunately, pinealoblastoma is usually fatal
with few survivors. Systemic chemoreduction for retinoblastoma may prevent trilateral
retinoblastoma.
Genetically-related second cancers can occur in survivors of bilateral
or heritable retinoblastoma.5,6
Patients with hereditary retinoblastoma have approximately a 5% chance of developing
a second cancer during the first 10 years of follow-up, 18% during the first 20
years, and 26% within 30 years.5
Second cancers most often include osteogenic sarcoma, spindle cell sarcoma, chondrosarcoma,
rhabdomyosarcoma, neuroblastoma, glioma, leukemia, sebaceous cell carcinoma, squamous
cell carcinoma, and malignant melanoma.
WHAT ARE THE OPHTHALMOSCOPIC FEATURES
OF RETINOBLASTOMA?
The clinical manifestations of retinoblastoma vary with the stage
of the disease.1,2 A small
retinoblastoma <2 mm in diameter appears transparent or slightly translucent
in the sensory retina.1,2
Larger tumors stimulate dilated retinal blood vessels feeding the tumor, foci of
intrinsic calcification and can produce subretinal fluid (exophytic pattern), subretinal
seeding, and vitreous seeding (endophytic pattern). Retinoblastoma of any size can
produce leukocoria, but this is most often seen with large tumors.
HOW DO WE CLASSIFY RETINOBLASTOMA?
Several classifications of retinoblastoma have been developed
including the Reese Ellsworth classification and the more recent International Classification
of Retinoblastoma (ICRB) (Table). The ICRB is useful in that it can assist in prediction
of chemoreduction success.7
KEEP IN MIND THE DIFFERENTIAL DIAGNOSIS
A number of ocular disorders in infants and children can resemble
retinoblastoma. The most common pseudoretinoblastomas included persistent hyperplastic
primary vitreous, Coats' disease, and ocular toxocariasis. It is important that
the diagnosis of retinoblastoma be excluded without question before treatment of
a pseudoretinoblastoma. Vitrectomy should be withheld until the diagnosis of retinoblastoma
is reliably excluded. Consultation with ocular oncologists experienced with retinoblastoma
could be helpful in confirming the suspected clinical diagnosis and excluding retinoblastoma.
WHAT ARE THE CHOICES FOR MANAGEMENT
OF RETINOBLASTOMA?
Management of retinoblastoma is tailored to each individual case
and based on the overall situation, including threat of metastatic disease, risks
for second cancers, systemic status, laterality of the disease, size and location
of the tumor(s), and estimated visual prognosis. The currently available treatment
methods include intravenous chemoreduction (carboplatin, etoposide, and vincristine)
subconjunctival carboplatin, thermotherapy, cryotherapy, laser photocoagulation,
plaque radiotherapy, external beam radiotherapy, and enucleation,8,9
For unilateral retinoblastoma, enucleation is performed in 75% of cases and conservative
treatment (nonenucleation methods) is possible in 25%. The reason for the high rate
of enucleation is that unilateral retinoblastoma is typically detected when the
tumor is advanced. For those with less advanced disease, chemoreduction plus focal
consolidation of each tumor with thermotherapy or cryotherapy, or the use of plaque
radiotherapy or other methods are beneficial. For bilateral retinoblastoma, chemoreduction
plus thermotherapy or cryotherapy is necessary in most cases and about 60% of patients
eventuate in loss of one eye.10-12
Enucleation of both eyes is only necessary in 1% of cases. Based on the ICRB, chemoreduction
success is achieved in 100% of group A, 93% of group B, 90% of group C, and 47%
of group D eyes (Figure 1).7
Group D eyes often require the addition of subconjunctival carboplatin as a local
boost in chemotherapy.13
CAN TUMORS RECUR AFTER CHEMOREDUCTION?
The main problem with chemoreduction is recurrence of vitreous
or subretinal seeds, usually remote from the main tumors.10-12
These seeds generally respond to initial chemoreduction, but later they can recur.
and require treatment with cryotherapy, thermotherapy, plaque radiotherapy, external
beam radiotherapy, or enucleation. It should also be realized that 24% of patients
develop new retinoblastomas during or after chemoreduction, generally in those who
present as infants and with family history of retinoblastoma.
CAN PLAQUE RADIOTHERAPY BE USED FOR
RETINOBLASTOMA?
 |
 |
Figure 1. Regression of macular retinoblastoma
following chemoreduction and focal foveal-sparing thermotherapy.
Top: Before treatment.
Bottom: After treatment, the tumor has remained regressed without
recurrence at 5 years. |
Plaque radiotherapy is a method of brachytherapy in which a radioactive
implant is placed on the sclera over the base of a retinoblastoma to irradiate the
tumor transclerally. It is limited to tumors <16 mm in base and 8 mm in thickness
and complete treatment can be achieved in approximately 4 days. Plaque radiotherapy
provides long-term tumor control in 90% of eyes when used as a primary treatment.14
In those eyes that need plaque radiotherapy for recurrence after chemoreduction,
complete control of the tumor is achieved in 96% of cases. All eyes treated with
plaque radiotherapy should be monitored for radiation maculopathy and papillopathy.
WHEN IS ENUCLEATION USED?
Enucleation is an important method for managing retinoblastoma.
Enucleation is employed for advanced disease with no hope for useful vision in the
affected eye or if there is a concern for invasion of the tumor into the optic nerve,
choroid, or orbit.
The technique of enucleation is to gently remove the eye intact
without seeding the malignancy into the orbit. After the globe is removed, fresh
tissue is harvested on a separate tray in the operating room for DNA analysis, using
a specific technique. The surgeon harvesting fresh tissue must remove the used gloves
and reglove after this step to avoid the risk of tumor contamination into the child's
orbit. If spillage onto the surgeons gown occurs, then complete regowning and regloving
is necessary. Following enucleation, an orbital implant is placed to provide a more
natural cosmetic appearance of the patient's artificial eye and to enable motility
of the prosthesis.15 There
are several available orbital implants including polymethylmethacrylate sphere,
coralline hydroxyapatite, polyethylene, and others.
In summary, retinoblastoma continues to be a challenge both diagnostically
and therapeutically. It is important to first clearly establish the correct diagnosis
before embarking on therapy. Many factors enter into the decision regarding management
such as patient age, tumor laterality, size, location, extent, and anticipated visual
prognosis.
Chemoreduction is an important conservative method for tumor control.
Enucleation still proves to be useful for advanced tumor.
REFERENCES
1. Shields JA, Shields CL. Management and prognosis of retinoblastoma.
In Shields JA, Shields CL., eds. Intraocular Tumors. A Text and Atlas. Philadelphia,
Pa: WB Saunders; 1992; 377-392.
2. Shields JA, Shields CL. Retinoblastoma. In Shields JA, Shields
CL, eds. Atlas of Intraocular Tumors. Philadelphia, Pa: Lipincott Williams
Wilkins; 1999:207-232.
3. Honavar SG, Singh AD, Shields CL,et al. Postenucleation adjuvant
therapy in high-risk retinoblastoma. Arch Ophthalmol. 2002;120:923-931.
4. Kivela T. Trilateral retinoblastoma: A meta-analysis of hereditary
retinoblastoma associated with primary ectopic intracranial retinoblastoma. J
Clin Oncol.1999; 17:1829-1837.
5. Roarty JD, McLean IW, Zimmerman LE. Incidence of second neoplasms
in patients with retinoblastoma. Ophthalmology 1988;95:1583-1587.
6. Wong FL, Boice JD Jr, Abramson DH, et al. Cancer incidence
after retinoblastoma. Radiation dose and sarcoma risk. JAMA. 1997;278:1262-1267.
7. Shields CL, Mashayekhi A, Au A, et al. The International Classification
of Retinoblastoma predicts chemoreduction success. Submitted for publication. Presented
at the International Society of Ocular Oncology; Whistler, Canada; September 2005
and the American Academy of Ophthalmology; Chicago, Ill;October 2005.
8. Shields CL, Mashayekhi A, Demirci H, Meadows AT, Shields JA.
A practical approach to management of retinoblastoma. Arch Ophthalmol. 2004.
In press.
9. Epstein J, Shields CL, Shields JA. Trends in the management
of retinoblastoma; Evaluation of 1,196 consecutive eyes during 1974-2001. J Pediatr
Ophthalmol Strab. 2003;40:196-203.
10. Shields CL, Meadows AT, Leahey AM, Shields JA. Continuing
challenges in the management of retinoblastoma with chemotherapy. Retina.
2004; 24:849-862.
11. Shields CL, Honavar SG Meadows AT, et al. Chemoreduction plus
focal therapy for retinoblastoma: Factors predictive of need for treatment with
external beam radiotherapy or enucleation. Am J Ophthalmol. 2002;133:657-664.
12. Shields CL, Mashayekhi A, Cater J, Shelil A, Meadows AT, Shields
JA. Chemoreduction for retinoblastoma Analysis of tumor control and risks for recurrence
in 457 tumors. Am J Ophthalmol. 2004;138:329-337.
13. Abramson DH, Frank CM, Dunkel IJ. A phase I/II study of subconjunctival
carboplatin for intraocular retinoblastoma. Ophthalmology. 1999;106:1947-1950.
14. Shields CL, Shields JA, Cater J, Othmane I, Singh AD, Micaily
B. Plaque radiotherapy for retinoblastoma: long term tumor control and treatment
complications in 208 tumors. Ophthalmology. 2001;108:2116-2121.
15. Shields CL, Shields JA, DePotter P, Singh AD. Lack of complications
of the hydroxyapatite orbital implant in 250 consecutive cases. Trans Am Ophthalmol
Soc. 1993;91:177-189.
Jerry Shields,
MD, is director, oncology services at Wills Eye Hospital and professor of ophthalmology
at Thomas Jefferson University. Carol Shields, MD, is co-director, oncology services
at Wills Eye Hospital and professor of ophthalmology at Thomas Jefferson University.
Support provided by the Macula Foundation, New York, NY and the Eye Tumor Research
Foundation, Philadelphia, PA. Neither author has any financial interest in the
information contained in this article.
Retinal Physician, Issue: March 2006