Intraocular Retinoblastoma Treatment
Treatment of retinoblastoma should be planned after the extent of the tumor within and outside both eyes is known. Treatment options consider both cure and preservation of sight.[1,2,3,4]
Treatment options for the involved eye include the following:
- Enucleation: Enucleation, if the tumor is massive or if there is little expectation for useful vision in the affected eye. Patients must be followed closely to monitor the remaining eye and assure there is no orbital recurrence of disease, particularly in the first 2 years after enucleation.[Level of evidence: 3iiA] Recurrence in the orbit is often associated with systemic disease (85%) and should be treated with aggressive therapy.
- Radiation therapy:
- External-beam radiation therapy (EBRT) with doses ranging from 35 Gy to 46 Gy. Because of the need to sedate young children and the intricacies of field planning, special expertise in pediatric radiation therapy is important. Newer methods of delivering EBRT are being used at many centers in an attempt to reduce adverse long-term effects. This includes intensity-modulated radiation therapy, stereotactic radiation therapy, and proton-beam radiation therapy (charged-particle radiation therapy).[6,7,8] EBRT in infants causes growth failure of the orbital bones and results in cosmetic deformity. It also increases the risk of second cancers in children with hereditary retinoblastoma.
- Brachytherapy with radioactive plaques for either focal unilateral presentations or recurrent disease following previous chemotherapy or EBRT.[9,10,11]
- Cryotherapy: Cryotherapy, used as primary therapy or with chemotherapy for tumors smaller than 4 disc diameters (DD) in the anterior portion of the retina.
- Laser therapy (Thermotherapy): Laser therapy may be used as primary therapy for small tumors or in combination with chemotherapy for larger tumors. Traditional photocoagulation, in which the laser was applied around the tumor, has given way to thermotherapy. Thermotherapy is delivered directly to the tumor surface via infrared wavelengths of light.
- Systemic chemotherapy: During the past 15 years, systemic chemotherapy to reduce tumor volume (chemoreduction) and to avoid the long-term effects of radiation therapy for patients with intraocular tumors has succeeded in rendering many eyes amenable to treatment with cryotherapy or laser therapy.[1,2,13]; [Level of evidence: 3iiDiii] Chemotherapy may also be continued or initiated with concurrent local control interventions. Factors such as tumor location (macula), patient age (patient older than 2 months), and tumor size correlate with responsiveness to chemotherapy.[15,16]
Multiagent chemotherapy is generally used, although carboplatin as a single agent causes shrinkage of retinoblastoma tumors.; [Level of evidence: 3iiiDiii] Most tumors treated with vincristine and carboplatin require additional local therapy;[1,2,13,19,20] the addition of etoposide to the chemotherapy regimen may improve outcome.[16,21] One study utilized carboplatin and etoposide with focal therapy, without vincristine, and found acceptable vision salvage rates for Reese-Ellsworth (R-E) Groups I through IV and International Classification Groups A and B retinoblastoma. The success rate of these trials varies from center to center, but overall, the rate is highest for discrete tumors without vitreous seeding (see below). Local tumor recurrence is not uncommon in the first few years after treatment, and can often be successfully treated with focal therapy. Among patients with hereditary disease, younger patients and those with a positive family history are more likely to form new tumors. Chemotherapy may treat small previously undetected lesions by slowing their growth and this may improve overall salvage with focal therapy.
There are data suggesting that the use of systemic chemotherapy may decrease the risk of development of trilateral retinoblastoma.
- Subtenon (subconjunctival) chemotherapy: Carboplatin is administered by the treating ophthalmologist into the subconjunctival space. This modality is undergoing testing in phase I and II trials and is generally used in conjunction with systemic chemotherapy and local ophthalmic therapies for retinoblastoma with vitreous seeding.[26,27] This approach offers some promise in this group of patients.
- Ophthalmic artery infusion of chemotherapy: Chemotherapy is being administered directly into the ophthalmic artery after insertion of a catheter through the femoral artery. This modality is undergoing testing in phase I and II trials at very specialized retinoblastoma treatment centers.