OBJECTIVEThe aim of this paper was to evaluate outcomes in patients with atypical meningiomas (AMs) treated with surgery alone compared with surgery and radiotherapy at initial diagnosis, or at the time of first recurrence.METHODSPatients with pathologically confirmed AMs treated at the University of Utah from 1991 to 2014 were retrospectively reviewed. Local control (LC), overall survival (OS), Karnofsky Performance Status (KPS), and toxicity were assessed. Outcomes for patients receiving adjuvant radiotherapy were compared with those for patients treated with surgery alone. Kaplan-Meier and the log-rank test for significance were used for LC and OS analyses.RESULTSFifty-nine patients with 63 tumors were reviewed. Fifty-two patients were alive at the time of analysis with a median follow-up of 42 months. LC for all tumors was 57% with a median time to local failure (TTLF) of 48 months. The median TTLF following surgery and radiotherapy was 180 months, compared with 46 months following surgery alone (p = 0.02). Excluding Simpson Grade IV (subtotal) resections, there remained an LC benefit with the addition of radiotherapy for Simpson Grade I, II, and III resected tumors (median TTLF 180 months after surgery and radiotherapy compared with 46 months with surgery alone [p = 0.002]). Patients treated at first recurrence following any initial therapy (either surgery alone or surgery and adjuvant radiotherapy) had a median TTLF of 26 months compared with 48 months for tumors treated at first diagnosis (p = 0.007). There were 2 Grade 3 toxicities and 1 Grade 4 toxicity associated with radiotherapy.CONCLUSIONSAdjuvant radiotherapy improves LC for AMs. The addition of adjuvant radiotherapy following even a Simpson Grade I, II, or III resection was found to confer an LC benefit. Recurrent disease is difficult to control, underscoring the importance of aggressive initial treatment.