Objective: This study aimed to investigate the relationship in bilateral retinoblastoma survivors between the incidence of second tumors and the age when external beam radiation (EBR) was used.
Design: A retrospective analysis of patients diagnosed with retinoblastoma was performed by examining records for background information and treatment information as well as reviewing documentation of patients with second nonocular tumors. Two telephone interviews were conducted for follow-up as well as inquiries directed to tumor registries and state databases.
Participants: The original study included 1729 patients treated in New York and Boston; the current study includes only the 1506 patients treated in New York. Of those, 816 patients were diagnosed with bilateral retinoblastoma, had sufficient treatment data to be useful, and survived at least 1 year from diagnosis.
Main outcome measures: The subjects were observed for evidence of the development of second nonocular tumors.
Results: There was a significant decrease in tumor-free survival among patients treated with EBR before the age of 12 months, but no significant difference between the group treated with EBR after the age of 12 months and the group not treated with EBR. For tumors in the field of radiation, patients treated with early EBR showed a significant decrease in tumor-free survival when compared to patients treated with late EBR, with no significant difference between late radiation and no radiation. There were no significant differences between groups for tumors out of the field of radiation. Significant differences attributable to the use of EBR were found only for tumors of the skull and face bones and for tumors of the soft tissue of the head.
Conclusions: The long-term effect of radiation treatment on survivors of bilateral retinoblastoma is to increase the incidence and affect the distribution of second tumors. However, no increased risk is observed for tumors out of the field of radiation among patients who underwent radiation, and the risk for tumors in the field of radiation is heavily dependent on the age at which EBR is given and may be acceptably small to the patient after the age of 12 months.