Association between adjuvant radiation therapy and overall survival in Pleomorphic Xanthoastrocytoma

Background: Pleomorphic Xanthoastrocytoma (PXA) is a low-grade central nervous system (CNS) tumor with a generally favorable prognosis. However, due to its rarity, optimal adjuvant treatment guidelines have not been established by large scale studies. In this study, we investigated the effect of adjuvant radiation therapy (RT) on overall survival (OS) in adult patients with PXA to help address this unanswered question. Methods: The National Cancer Database (NCDB) was used to identify adult patients (age ≥ 18 years old) diagnosed with histologically confirmed grade II PXA (2004–2016). Patient demographics, tumor characteristics, and treatment information were collected. Kaplan-Meier curves were generated to study OS, and factors that affected OS were identified using a multivariate Cox proportional hazards (CPH) model. Results: A total of 546 patients were identified. The average age of patients at diagnosis was 36.6 years old, and overall median survival was 128.6 months. RT was used to treat 179 (33.3 %) patients. Those who received RT had a shorter median OS (33.3 months) compared to those who did not (>128.6 months, p < 0.001). Our multivariate model demonstrated receiving RT was independently associated with a significantly higher risk of death (hazard ratio [HR] = 4.28, 95 % confidence interval [CI] = 1.77−10.38, p = .0013). Patients ≥65 years of age also demonstrated significantly higher risk of death (HR = 2.20, CI = 1.54−4.16, p = .006) and had a decreased median OS (26.0 months). Conclusion: In adults with PXA, treatment with RT is independently associated with a significantly higher risk of mortality. The routine use of this modality in treating PXA warrants further study.