Effect of radiation therapy on overall survival following subtotal resection of adult pilocytic astrocytoma

Objective: Pilocytic astrocytoma (PCA) is a low-grade glioma that primarily presents in children, but can also present in adulthood. Ideal primary treatment for PCA is gross total resection. However, for patients who are only able to undergo subtotal resection, the optimal course of post-operative therapy remains unclear. We investigated the association of patient characteristics and radiation therapy (RT) with overall survival specifically for adult PCA patients who underwent subtotal tumor resection. Methods: Information on adult patients (age ≥18 years old) who underwent subtotal PCA resection between 2004 and 2016 was collected from the National Cancer Database (NCDB). A multivariate Cox proportional hazards model was utilized to determine factors associated with overall survival. Results: A total of 451 patients were identified. The mean age of our patient cohort was 36.8 years old, and the majority of patients (83.4%) did not receive RT following subtotal PCA resection. Overall median survival was >93.8 months. On multivariate analysis, patients who were older at diagnosis (hazard ratio [HR] = 1.04, 95% confidence interval [CI] = 1.02–1.06, p < 0.01), black (HR = 2.35, CI = 1.05–5.23, p = 0.037), had a Charlson/Deyo comorbidity score ≥ 1 (HR = 2.27, CI = 1.00–5.14, p = 0.049), or received RT during their initial treatment (HR = 3.77, CI = 1.77–8.03, p < 0.01) had a significantly higher risk of death following subtotal PCA resection. Conclusion: Post-operative RT was associated with a significantly higher risk of death among adults who underwent subtotal PCA resection. Our findings provide support for further inquiry into the efficacy of RT within this patient population.