Abstract
Purpose::
To evaluate the efficacy of Iodine 125 plaque radiotherapy for recurrent retinoblastoma presenting with active localized vitreous seeding after chemoreduction.
Methods::
Prospective nonrandomized and non comparative case series managed at the Ocular Oncology Unit from September 1997 to September 2006. Eligibility criteria included recurrent localized vitreous seeds alone or with retinal retinoblastoma tumor extending less than 3 clock hours (15 mm) in largest basal diameter and less than 8.0 mm in height in the vitreous cavity documented after 6 cycles of intravenous chemoreduction (vincristine, etoposide, and carboplatin). 14 children (unilateral non hereditary retinoblastoma in 4 cases and bilateral hereditary retinoblastoma in 10 cases) presented with 14 eyes containing 17 recurrent vitreous retinoblastoma tumors. The radiation protocol was designed to include the localized vitreous seeding with adequate dose of 40 Gy at tumor apex and delivered with an episcleral customized iodine 125 plaque. Main outcome measures : Tumor recurrence and treatment complications.
Results::
The mean child age at plaque treatment was 21 months. Recurrence (active vitreous seeds alone [3] and active vitreous seeds with retinal tumor [14]) was detected after a mean interval of 6 months after chemoreduction. The mean largest basal tumor diameter was 12 mm (range, 6 to 15 mm) and tumor thickness 6 mm (range, 4 to 8 mm). The mean distance to the disc was 8 mm and to the fovea 8.5 mm. After a mean total follow-up of 49 months, tumor recurrence was documented within the 40 Gy-isodose curve in one eye (6%). Final enucleation was eventually performed in 3 eyes (18%) as treatment of tumor recurrence after plaque radiotherapy in one eye and treatment of tumor recurrence elsewhere within the globe in 2 eyes. Using Kaplan Meier estimates, tumor control were 94 % at 1 year, and 85% at 5 years and globe salvage rate was 92% at 1 year, and 81% at 5 years. Radiation retinopathy and cataract was documented in 6 eyes (35%) and in 7 eyes (41%) respectively.
Conclusions::
Iodine 125 plaque radiotherapy for selected recurrent retinoblastoma with localized vitreous seeding after chemoreduction provides tumor control in 85% of cases and globe salvation in 81% at 5 years of follow-up. It is particularly useful for those localized recurrent vitreous seeding that fail treatment with chemoreduction.
Keywords: tumors • retinoblastoma • radiation therapy