Long-term outcomes following proton therapy for non-metastatic central nervous system germinoma in children and adolescents

Abstract

Background/PurposeRadiation is a key component in the treatment of central nervous system pure germinoma (PG) in children and adolescents. Proton therapy (PT) improves normal tissue sparing and potentially reduces adverse effects (AE). The aim of this study was to present the largest single institution experience utilizing PT for the management of PG. Materials MethodsWe enrolled 35 non-metastatic patients with PG that were treated with PT at our institution between July 2007 – September 2021. Most received induction chemotherapy (n = 31, 89 %) and whole ventricular irradiation with an involved field boost (n = 29, 83 %). The most common total dose was 30 CGE (n = 18, 51.4 %). We utilized the cumulative incidence method to estimate local control (LC), freedom from distant metastases (FFDM), freedom from progression (FFP), and overall survival (OS). Treatment related toxicity was assessed per CTCAE version 5. ResultsMedian follow-up was 6.2 years (range, 0.9–––15.2). The 10-year Kaplan-Meier estimates for LC, FFDM, FFP, and OS were 100 %, 100 %, 100 %, and 94 % respectively. The most common AE were hearing impairment requiring hearing aids (n = 3), transient hypersomnia requiring medication (n = 3), and new onset endocrinopathy (n = 1). Of the 23 evaluable patients ≥ 18 years old at last follow-up, 8 were high school graduates/in college, 8 college graduates, and 7 others gainfully employed. ConclusionsWhen utilized in modern multimodality treatment of non-metastatic PG, the precise dosimetry of PT does not compromise disease control. Although serious radiation side effects are rare, the 100% cure rate supports further investigation into selective radiation dose and volume de-escalation.