Medical student Northwestern University Feinberg School of Medicine
Introduction: Pleomorphic xanthoastrocytoma (PXA) is a rare circumscribed astrocytic tumor. While maximal safe resection is often the first goal of treatment, the role of adjuvant therapy remains uncertain. Molecular characterization has identified a BRAF mutation that is targetable with inhibitors.
Methods: Patients with pathologically confirmed PXA treated at our institution (1990-2019) were identified. Demographics, tumor grade, treatment information, and outcomes data were collected. Kaplan-Meier estimates summarized progression-free survival (PFS) and overall survival (OS). Outcomes were stratified by tumor grade and extent of resection. Cox regression and log-rank testing were performed.
Results: We identified 17 patients with pathologically confirmed PXA. Of the 17 patients, 2 patients were excluded due to incomplete treatment information or < 6m of follow up; 15 patients were analyzed. Six patients had grade 2 PXA and 9 had grade 3 anaplastic PXA. The 2-year and 5-year PFS for the cohort was 57% and 33%, respectively; 2-year and 5-year OS was 93% and 75%, respectively. Patients with grade 2 tumors exhibited superior PFS compared to those with grade 3 tumors (2-year PFS: 100% vs. 28%, 5-year PFS: 60% vs. 14%), hazard ratio, 5.09 (95% CI:1.06-24.50), p = 0.02. Undergoing a GTR yielded improved outcomes (hazard ratio: 0.38, p = 0.15). All but one (89%) of the grade 3 patients underwent RT. Seven lesions (3 grade 2 and 4 grade 3) had a known BRAF mutation; these had better PFS compared to BRAF wild-type lesions at 5-years (43% vs 19%); however, this was not statistically significant, hazard ratio 0.96 (p=0.95).
Conclusion : Given only one recurrence and good overall survival among the grade 2 patients, GTR followed by observation is likely appropriate in this population. The poor survival of grade 3 patients suggests the need for a more aggressive treatment strategy, including maximal resection followed by adjuvant therapy.
