Clinical factors and conventional MRI may independently predict progression-free survival and overall survival in adult pilocytic astrocytomas

Purpose: Pilocytic astrocytoma (PA) is rare in adults, and only limited knowledge on the clinical course and prognosis has been available. The combination of clinical information and comprehensive imaging parameters could be used for accurate prognostic stratification in adult PA patients. This study was conducted to predict the prognostic factors from clinical information and conventional magnetic resonance imaging (MRI) features in adult PAs. Methods: A total of 56 adult PA patients were enrolled in the institutional cohort. Clinical characteristics including age, sex, anaplastic PA, presence of neurofibromatosis type 1, Karnofsky performance status, extent of resection, and postoperative treatment were collected. MRI characteristics including major axis length, tumor location, presence of the typical ‘cystic mass with enhancing mural nodule appearance’, proportion of enhancing tumor, the proportion of edema, conspicuity of the nonenhancing margin, and presence of a cyst were evaluated. Univariable and multivariable Cox proportional hazard modeling were performed. Results: The 5-year progression-free survival (PFS) and overall survival (OS) rates were 83.9% and 91.l%, respectively. On univariable analysis, older age, larger proportion of edema, and poor definition of nonenhancing margin were predictors of shorter PFS and OS, respectively (all Ps <.05). On multivariable analysis, older age (hazard ratio [HR] = 1.04, P =.014; HR = 1.14, P =.030) and poor definition of nonenhancing margin (HR = 3.66, P =.027; HR = 24.30, P =.024) were independent variables for shorter PFS and OS, respectively. Conclusion: Age and the margin of the nonenhancing part of the tumor may be useful biomarkers for predicting the outcome in adult PAs.