External Beam Radiation Therapy for Retinoblastoma Resistant to Chemotherapy and Focal Treatment: Outcome and Predictive Factors

External Beam Radiation Therapy for Retinoblastoma Resistant to Chemotherapy and Focal Treatment: Outcome and Predictive Factors

Abstract:

Purpose:

To evaluate the outcome of external beam radiation therapy (EBRT) for treatment of retinoblastoma resistant to chemotherapy and focal therapy.

Methods and Materials:

A retrospective case series of 24 eyes for 20 retinoblastoma patients treated by EBRT after failure of tumor control by chemotherapy and focal therapy. The main outcome measures included: international intraocular retinoblastoma stage (IIRC) and Reese Ellsworth (RE) stage, tumor seeding, treatment modalities, eye salvage, and survival.

Results:

The median age at diagnosis was 12 months. There were 12 (60%) males and 16 (80%) bilateral cases. All eyes were treated initially by systemic chemotherapy (range: 6-8 cycles). The dose of 45Gy was used in all eyes. The mean follow-up was 55months. Eye salvage rate after EBRT was 45% (11eyes); 67% ( 2/3) for IIRC group B, 63% (5/8) for group C, and 31% (4/13) for group D eyes. Vitreous seeds and tumor stage migration during management by chemotherapy were the most important significant predictive factors for tumor control (p=0.0327 and 0.0333 consecutively). Post EBRT complication rate was 80% (19/24) including; retinal detachment (3), vitreous hemorrhage (4), neovascular glaucoma (1), cataract (16), and radiation retinopathy (2).

Conclusion:

Eyes with retinoblastoma that failed chemotherapy were controlled with EBRT. However the presence of vitreous seeds, stage migration during chemotherapy, as well as good vision in the other eye may not justify the known risks of EBRT.