UNILATERAL RETINOBLASTOMA - NEW INTRAOCULAR TUMORS AFTER TREATMENT

A retrospective chart review of 427 eyes diagnosed with unilateral ret inoblastoma was performed to determine which eyes, which patients, and when new intraocular tumours would develop after treatment. Mean foll ow up was 8.16 years. Twenty five (6%) of 427 unilateral retinoblastom a patients developed new intraocular tumours after treatment. Five (1% ) unilateral patients who were previously treated with enucleation dev eloped new tumours (in the fellow eye). Fifteen (24%) unilateral patie nts who were previously treated with external beam radiation developed new tumours (equally in either eye). New tumours did not develop in t he macula of either eye. The relative risk of developing new intraocul ar tumours after treatment was 16% in patients diagnosed before 1 year old and 2.2% for patients diagnosed after 1 year old (p<0.001). The m ean time to onset for the development of new tumours after treatment w as 0.74 years; no new tumours appeared after 7.5 years of age. Those p atients who are diagnosed with unilateral retinoblastoma in the first 6 months of life and have a family history of the disease are at great est risk of developing new intraocular tumours.