Retinoblastoma

Incidence

  • 14% of infants cancers
  • 300 cases in US per year

Presentation

leuko
  • Leukocoria is a common presenting symptom
retina
CT
  • intraocular calcification in the right eye associated with retinoblastoma

Trilateral Disease

  • Bilateral retinoblastoma associated with ectompic retinoblastoma of Pineal or suprasellar region
  • The intracranial lesion can cause signs of ICP or, when the lesion is suprasellar diabetes insipidus.
  • Occurs 3-4 years aftter diagnosis.
  • Treatment of trilateral disease with surgery alone or in combination with radiotherapy resulted in no long-term survivors.

Comparison of Unilateral and Bilateral

Bilateral Unilateral
usually Multifocal Unifocal
% of retinoblastoma 40%
• 25% inherited from carrier
• 75% "de novo"
60%
Mutation Rb1 somatic mutation
time to diagnosis 14-16 mo 29-30 mo
5-OS 86.4 89.9 (NS)[1]

Staging

  • Group I (Very Favorable)
    • < 4 dd, all at or behind the equator
  • Group II (Favorable)
    • 4-10 dd at or behind the equator (behind if multiple lesion)
  • Group III (doubtful)
    • Anterior lesion
    • > 10 dd, solitary, behind the equator
  • Group IV (Unfavorable)
    • >10 dd, multiple lesion
    • Anterior to ora serrata
  • Group V (Very Unfavorable)
    • > 1/2 retina or vitreous seeding
  • Reese-Ellworth classification is used to see if the eye can be conserved and not so much for prognosis
  • Ocular preservation 95% for stage I-II and 50% for III-V.

Treatment

Chemotherapy

  • Carboplatin, vincristine based therapy
  • purpose is to reduce bulk of of the tumor
chemo

Consolidation Therapy

focal
  • diode laser (TTT) (small tumor recurrence)
  • photocoagulation (< 4 dd)
  • cryotherapy (< 4 dd)
  • brachytherapy (4-10 dd discreet tumors)
  • enucleation for "bulky" tumor

External Beam Radiation

Indication

  • recurrent (Episcleral plaque is also a possibility)
  • high-risk ocular or regional involvement detected at the time of enucleation

Technique

  • 40-45 Gy to the retinal analage and vitreous

Results

  • Group I-III disease control 70-80%
  • Schipper from Utrecht
    • 94% vision preservation in group I-III by using anatomically precise lateral linear accelerator technique with ocular fixation and narrowly defined target volume. (45 Gy in 3 Gy per fraction)
    • Group IV 79% preservation
    • Group V 0%

Episcleral Plaque Brachytherapy

Picture

plaque

Indication

  • Consolidation
    • 2-16 mm diameter tumor
    • located > 3 mm from optic disc or fovea
    • < 10 mm thickness
    • small amount of vitreous seeding over tumor apex is allowed
  • Recurrent

Method

  • 40 Gy to apex at 40-50 cGy per hour with RT alone
  • 25-30 Gy when used with chemotherapy
  • 1.5 - 2.0 mm marginon either side of the basal diameter
  • Co-60, I-125, Ir-192, Ru 109 plaques: I-125 is most widely used in US.

Results

  • Lesion conrol 86-95%
  • 13% recurrence with 5 month mean interval
  • The high rate of recurrence has limited enthusiasm for brachytherapy in cases with bilateral presentations; however, renewed interest in this modality has been shown in conjunction with chemotherapy.

Delayed Effects

  • Radiation treatment in patients with hereditary retinoblastoma results in secondary malignancy (osteosarcoma) in 38% at 50 years vs 21% treated without radiation
  • Secondary malignancy risk for non-hereditary retinoblastoma at 50 years is 5.69%

Retreatment after EBRT

  • small and favorably located turmors
    • photocoagulation
    • cryotherapy
    • radioactive plaque
  • If not (small and favorably located)
    • re-irradiation with external beam is possible [1]
Bibliography
1. Abramson DH, Ellsworth RM, Rosenblatt M, Tretter P, Jerb B, Kitchin FD. Retreatment of retinoblastoma with external beam irradiation. Arch Ophthalmol 1982; 100: 127-1260.
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