Outcome following initial external beam radiotherapy in patients with Reese-Ellsworth group Vb retinoblastoma.

Objective: To describe patient and ocular outcomes following initial treatment with external beam radiotherapy (EBT) in eyes with Reese-Ellsworth group Vb retinoblastoma.
Methods: Retrospective case series (from January 1, 1979, to February 28, 2002). The Kaplan-Meier method was used to analyze survival (ocular and patient) and incidence (second cancer) data.
Results: Two hundred forty-three patients with 1 or more Reese-Ellsworth group Vb eyes were identified. Of 284 group Vb eyes, 63 (22.2%) initially received EBT, vs 172 (60.6%) that were initially enucleated. Of the 63 radiated group Vb eyes, 31 (49.2%) had no further tumor growth, 26 (41.3%) developed a recurrence, and 8 (12.7%) developed a new tumor. Of the 63 radiated group Vb eyes, 33 (52.4%) developed ocular complications. The ocular survival rate of radiated group Vb eyes was 81.4% at 1 year and 53.4% at 10 years. Twenty-eight radiated group Vb eyes survived to the last follow-up with visual acuity information. Thirteen patients developed second cancers, 11 in the field of radiation. The probability of developing a second cancer following initial EBT for group Vb disease in patients with bilateral disease was 29.7% by 10 years after diagnosis. Survival from second cancers in patients with bilateral disease initially receiving EBT for group Vb disease was 93.6% at 5 years and 52.6% at 18(1/4) years. No patient with unilateral disease developed a second cancer. Deaths due to metastatic retinoblastoma were uncommon.
Conclusions: To our knowledge, this is the first study focusing exclusively on group Vb eyes treated initially with EBT, most of which were salvaged with vision. Outcome data provided herein are clinically relevant when choosing treatment options for advanced intraocular retinoblastoma.