Abstract 5050: Case Report: A 17-Year-old Patient Developed Glioblastoma Secondary to Intracranial Germ Cell Tumor and Was Stabilized with Chemoradiotherapy Combined with Tumor Treating Fields

Background: Germ Cell Tumor (GCT) is a rare intracranial tumor occurring in children and young adults. Some patients with GCT are curable with radiotherapy and chemotherapy. Due to long-term survival, the tumor secondary to radiotherapy is of concern. The treatment of the secondary tumor is less elaborated and worth exploring. Case Presentation: Here we report a patient with GCT who developed radiotherapy-induced glioblastoma. He was diagnosed as pineal gland GCT at the age of 12. Afterwards, he underwent a set of treatments, including chemotherapy, radiotherapy, and surgery. Unfortunately, after 5 years of tumor-free survival, he developed an intracranial mass involved the right thalamus and brainstem, around pineal region. The GCT recurrence was firstly considered, however, the failure of 7 cycles of chemotherapy drew attention. Then brain biopsy underwent by ROSA robot showed high-grade glioma. Next Generation Sequencing showed IDH-wildtype, MGMT methylation, CDKN2A/B homozygous deletion, EGFR amplification, the +7/−10 signature, which supported the diagnosis of glioblastoma. Resection operation is not applicable for this patient as the involvement of thalamus and brainstem. Considering the difficulty of treatment and poor prognosis of glioblastoma, re-radiotherapy is a feasible choice. Chemoradiotherapy with Tumor Treating Fields (TTFields) is a innovative try for secondary glioblastoma in a 17-year-old patient. After the combination therapy, the intracranial mass went regression and the patient has lived for more than 1 years. Conclusions: For the patients with brain tumor who anticipate long-term survival, the secondary tumor after radiotherapy is of concern. Secondary Glioblastoma is rare and difficult to treat. Chemoradiotherapy with TTFields is a feasible and safe treatment option for some patients, but we need more evidence to support. Citation Format: Shaoqun Li, Mingyao Lai, Hainan Li, Juan Li, Jiangfen Zhou, Qingjun Hu, Minting Ye, Ruyu Ai, Junqiao Zhu, Lijun Huang, Linbo Cai. Case report: A 17-year-old patient developed glioblastoma secondary to intracranial germ cell tumor and was stabilized with chemoradiotherapy combined with Tumor Treating Fields. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5050.