Revisiting Adjuvant Radiotherapy After Gross Total Resection of World Health Organization Grade II Meningioma

BACKGROUND: Atypical meningioma is a World Health Organization grade II tumor with intermediate prognosis and risk of recurrence. Optimal management after gross total resection (GTR) is controversial, with observation versus adjuvant radiotherapy (RT) contentiously debated. METHODS: Pathologic review was performed of all atypical meningiomas diagnosed at our institution from 1988 to 2011. Retrospective chart review documented patient demographics, extent of surgical resection, history of radiation therapy, progression-free survival (PFS), and overall survival (OS). A supplemental systematic literature review was completed in which English-language articles published since 1979 comparing observation and RT after GTR of atypical meningioma were surveyed. RESULTS: Sixty-nine patients met inclusion criteria. Sixty-one underwent observation, and 8 received RT. Overall, 15 observation and 3 patients undergoing RT experienced tumor recurrence (5-year PFS 79% vs. 88%; P = 0.67); 19 observation and 2 patients undergoing RT died (5-year OS 89% vs. 83%; P = 0.68). Systematic review identified 9 preceding studies reporting extractable data comparing observation and RT outcomes after GTR. Recurrence was 18% and 19% after observation and RT (P = 0.9); total survival was 84% and 93% (P = 0.2). At 5 years, PFS was 81% after observation and 88% after RT (P = 0.2), whereas survival was 87% after observation and 96% after RT (P = 0.4). CONCLUSIONS: Observation alone after GTR of atypical meningioma was not associated with increased risk of tumor recurrence or mortality. Although some preceding authors advocate for RT based on empiric experience, a systematic review also suggests that observation may provide equivalent PFS and OS to RT. Taken together, these findings indicate that observation after GTR may be a safe alternative to RT.