Trilateral retinoblastoma--incidence and outcome: a decade of experience.

PURPOSE: This report examines the incidence and outcome of trilateral retinoblastoma in children treated for retinoblastoma. A group of patients who are at highest risk for the development of trilateral retinoblastoma is defined. METHODS AND MATERIALS: Between 1979 and 1990, 117 children were treated with external beam radiation therapy for retinoblastoma, (97/117, bilateral). Median follow-up time was 68 months. The median age at diagnosis was 7 months.
RESULTS: Six cases of trilateral retinoblastoma were identified. The incidence of trilateral retinoblastoma in children with bilateral retinoblastoma was 6% (6/97) and 10% in those with a family history of retinoblastoma. The median age at diagnosis of RB in the children with trilateral retinoblastoma, was 3 months, younger than the median age of the entire retinoblastoma group. In all cases, the pineal region was excluded from the radiotherapy fields. Treatment for the trilateral retinoblastoma consisted of craniospinal axis radiation therapy and chemotherapy in three patients, chemotherapy alone in two, and no treatment in one. All patients died from this disease. Overall, of the 117 children treated at our institution for retinoblastoma with a median follow-up of 68 months, 12 have died. Trilateral retinoblastoma was the major cause of death, accounting for 50% (6/12) of deaths.
CONCLUSION: Trilateral retinoblastoma is a major and under-appreciated cause of mortality in the first 5 years after the diagnosis of bilateral retinoblastoma. A more aggressive approach toward screening a defined population of childhood retinoblastoma survivors may be warranted.