RARE-31. Radiation induced malignancy associated with pediatric craniopharyngioma: a single institution experience

Abstract BACKGROUND: Therapy for pediatric craniopharyngioma, a rare suprasellar tumor, includes surgical resection with consideration for intracranial radiation. Radiation is associated with increased risk of secondary malignancies. Between 2000 and 2021, 81 pediatric patients with craniopharyngioma were treated at our institution; 3 of 54 (5.6%) who received radiation therapy(RT) developed secondary malignancy within the treatment field. CASE DESCRIPTIONS: In all 3 cases, initial imaging demonstrated cystic/solid suprasellar mass and underwent resection; pathology revealed calcifications and wet keratin consistent with craniopharyngioma. None had known cancer predispositions. The first patient (male), presented at 4-years-old with headaches. He underwent subtotal resection (STR) with cyst fenestration(w/CF) and received 55.8Gy photon 3D-Conformal RT. Six-years later, the tumor progressed (edge of RT field). Patient underwent a second STRw/CF and fractionated RT(50.4Gy). Both pathologies were consistent with(c/w) papillary craniopharyngioma. Eight-years from first RT, progression occurred again within the RTfield; pathology revealed an (adeno)squamous carcinoma. The second patient, a 5-year-old female, presented with vision loss, underwent partial resection and received 54Gy focal proton therapy for adamantinonatous craniopharyngioma. Almost 5-years later, an unresectable right basal ganglia/globus pallidus mass was noted in the 30-54Gy field. Pathology was c/w anaplastic astrocytoma(AA). The third, a 9-year-old female was treated with 54Gy photon radiation and 7 years later had evidence of increasing mass. Pathology revealed high-grade-diffuse-glioma(HGDG). Molecular analysis of AA/HGDG both revealed PDGFRA amplification and CDKN2A/B homozygous loss. DISCUSSION/CONCLUSION: Malignant CNS tumors are reported following radiotherapy for a variety of primary CNS lesions. While radiation is a valuable therapy in achieving long-term disease control of pediatric craniopharyngiomas, it is important to understand the risk of developing secondary malignant neoplasms. Our report adds to the body of literature describing secondary malignancies post radiation therapy for the treatment of pediatric craniopharyngioma.