Plaque radiotherapy for retinoblastoma: long-term tumor control and treatment complications in 208 tumors.

OBJECTIVE

To evaluate the clinical factors predictive for tumor recurrence and treatment complications in a large series of children who underwent plaque radiotherapy for retinoblastoma.

DESIGN

Retrospective, noncomparative case series.

PARTICIPANTS

The participants included 141 children with retinoblastoma who were managed on the Oncology Service at Wills Eye Hospital with plaque radiotherapy between July 1976 and June 1999.

MAIN OUTCOME MEASURES

Tumor recurrence and treatment complications.

RESULTS

There were 208 tumors managed with plaque radiotherapy. The mean patient age at plaque treatment was 19 months. Prior treatment to the retinoblastoma of concern was delivered to 148 tumors (71%) and included various combinations of treatments such as intravenous chemoreduction, external beam radiotherapy, laser photocoagulation, thermotherapy, and cryotherapy. For 72 retinoblastomas (35%), more than one therapeutic method had failed to achieve tumor control before the use of plaque radiotherapy. Of the 208 retinoblastomas managed with plaque radiotherapy, Kaplan-Meier estimates of tumor control were 83% at 1 year and 79% at 5 years. Of the 60 tumors treated only with plaque radiotherapy (primary treatment), recurrence at 1 year was 12%. Of the 148 tumors treated after failure of other methods (secondary treatment), specific Kaplan-Meier estimates of tumor recurrence at 1 year was detected in 8% of tumors previously treated with chemoreduction, 25% of tumors previously treated with external beam radiotherapy, 34% tumors previously treated with both chemoreduction and external beam radiotherapy, and 8% of tumors previously treated with laser photocoagulation, thermotherapy, or cryotherapy (methods other than chemoreduction and external beam radiotherapy). Using multivariable analysis, the risks for tumor recurrence included the presence of tumor seeds in the vitreous, presence of subretinal tumor seeds, and increasing patient age. Using Kaplan-Meier estimates, radiation complications at 5 years of follow-up included nonproliferative retinopathy in 27%, proliferative retinopathy in 15%, maculopathy in 25%, papillopathy in 26%, cataract in 31%, glaucoma in 11%, and scleral necrosis in 0%.

CONCLUSIONS

Plaque radiotherapy for retinoblastoma provides tumor control in 79% of cases at 5 years of follow-up. It is particularly useful for those tumors that fail treatment with chemoreduction, laser photocoagulation, thermotherapy, and cryotherapy. Tumors in young patients without vitreous or subretinal seeding show the best long-term control.