Background: The efficacies of adjuvant stereotactic radiosurgery (SRS) or external beam radiation therapy (EBRT) for atypical meningiomas (AM) following subtotal resection (STR) remain unclear.
Objective: To analyze clinical, histopathological, and radiographic features associated with progression in AM patients following STR.
Methods: Fifty-nine primary AMs after STR were examined for predictors of progression, including the impact of SRS and EBRT, in a retrospective cohort study.
Results: Twenty-seven patients (46%) progressed after STR (median 30 months). On univariate analysis, spontaneous necrosis positively (hazard ratio [HR] = 5.2, p = 0.006) and adjuvant radiation negatively (HR = 0.3, p = 0.009) correlated with progression; on multivariate analysis, only adjuvant radiation remained independently significant (HR = 0.3, p = 0.006). SRS and EBRT were associated with greater local control (LC) (p = 0.02) and progression-free survival (PFS) (p = 0.007). The 2-, 5-, and 10-year actuarial LC rates after STR vs. STR/EBRT were 60%, 34%, and 34% and 96%, 65%, and 45%. The 2-, 5-, and 10-year actuarial PFS rates after STR vs. STR/EBRT were 60%, 30%, and 26% and 96%, 65%, and 45%. Compared to STR alone, adjuvant radiation therapy significantly improved LC in AMs that lack spontaneous necrosis (p = 0.003), but did not improve LC in AMs with spontaneous necrosis (p = 0.6).
Conclusion: Adjuvant SRS or EBRT improved LC of AMs after STR but only for tumors without spontaneous necrosis. Spontaneous necrosis may aid in decisions to administer adjuvant SRS or EBRT after STR of AMs.
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