Ocular preservation after 36 Gy external beam radiation therapy for retinoblastoma.

Abstract

The purpose of this study was to document the ocular preservation rate after 36 Gy external beam radiation therapy (EBRT) for retinoblastoma. Forty-nine eyes of 38 patients were treated with a median dose of 36 Gy EBRT. The patient population included 7 unilateral and 31 bilateral presentations, with a median age at diagnosis of 4 months. Eyes enucleated at the time of diagnosis or treated with other measures were not included in the analysis of ocular preservation. The median age at EBRT was 8 months. Patients were monitored for progression of disease after EBRT and second malignant neoplasms. The median follow-up was 88.6 months, with an estimated ocular preservation rate of 82.0% +/- 5% at 10 years. There was a difference in the ocular preservation rates for patients with advanced disease (Reese-Ellsworth group III-V) compared with early disease. Metastatic disease developed in two patients, and a second malignant neoplasm developed in three. Patients treated with en face electrons experienced a lower 5-year estimate of ocular preservation than those treated with photons, although patients treated with electrons were more likely to have advanced disease. The use of low-dose EBRT (36 Gy) results in ocular preservation rates that are comparable to those of high-dose EBRT. The use of electrons requires careful treatment planning and computerized dosimetry.