LG-36: LOW GRADE ASTROCYTOMA: A RARE SECOND TUMOR IN RETINOBLASTOMA SURVIVORS

BACKGROUND: Retinoblastoma is the most common pediatric intraocular malignancy. Survivors with a germline RB1 mutation are at elevated risk for secondary malignancy, but their risk for low grade astrocytoma (LGA) is unknown. METHODS: We performed a PubMed search using the phrase “retinoblastoma and low grade astrocytoma” and a retrospective review of the MSKCC and the National Cancer Institute databases. RESULTS: The PubMed search did not identify any relevant publications. The database review revealed that 3 of the 813 5-year survivors of hereditary retinoblastoma were diagnosed with a LGA. The incidence of LGA (US SEER population) for 1-19 year olds is 0.2/100,000 and for 20-34 year olds is 0.4/100,000. All 3 cases were diagnosed with bilateral retinoblastoma during infancy. Patient 1 underwent enucleation of the left eye, carboplatin chemotherapy, and external beam radiation therapy (EBRT) to the right eye for recurrence. He progressed with trilateral disease which required chemotherapy, autologous peripheral stem cell rescue, and 4 doses of intrathecal radioimmunotherapy. He developed a cerebellar LGA 13 years after diagnosis. Patient 2 was treated with enucleation of one eye and EBRT. She developed a cerebellar LGA 20 years after diagnosis. Patient 3 required enucleation of the left eye and cryotherapy to the right eye and developed a temporal LGA 23 years after diagnosis. CONCLUSIONS: LGA appear to occur more frequently in patients with a germline RB1 mutation than in the general population. This may be a result of loss of cell-cycle control. Long term surveillance imaging may be considered.