Conditional Analysis on New Tumor Formation with Solitary Unilateral Retinoblastoma in 482 Consecutive Patients

PURPOSE: The objective of the study was to understand dynamic risk (conditional analysis based on patient age) for new tumor development in patients with solitary unilateral retinoblastoma. METHODS: This was a retrospective analysis. RESULTS: Of 482 patients with solitary unilateral retinoblastoma, 55 new tumors developed in 20 patients (4%). Comparison (new tumor vs. no new tumor development) revealed those with new tumor demonstrated younger mean age at presentation (10 vs. 36 months, CONCLUSION: Children (≤24 months) with solitary unilateral retinoblastoma showed decreasing risk for new tumors up to 24 months of life. Later onset of new tumor was more likely located in preequatorial region.