Impact of postoperative radiotherapy on recurrence of primary intracranial atypical meningiomas

Background: Atypical meningiomas (WHO grade II) have high recurrence rate. However, data on the effect of radiotherapy (RT) is still conflicting. The aim of this study was to evaluate the influence of postoperative RT on the recurrence of primary atypical intracranial meningiomas. Methods: The medical records of all patients who underwent surgery (2007–2017 in 4 neurosurgical departments) for a histologically diagnosed primary atypical meningioma were reviewed to assess progression-free survival (PFS) and prognostic factors. Results: This analysis included 258 patients with a median age of 60 years (54.7% female). The predominant tumor locations were convexity and falx (60.9%) followed by the skull base (37.2%). Simpson grade I–II resection was achieved in 194 (75.2%) patients, Simpson grade III–IV in 53 patients (20.5%). Tumor progressed in 54 cases (20.9%). Postoperative RT was performed in 46 cases (17.8%). RT was more often applied after incomplete resection (37.7% vs. 13.4% Simpson III–IV vs. I–II). A multivariate analysis showed a significantly shorter PFS associated with Simpson III–IV [HR 1.19, (95% CI) 1.09–1.29, p < 0.001] and age > 65 years [HR 2.89, (95% CI) 1.56–5.33, p = 0.001]. A subgroup analysis with a minimal follow-up of 36 months revealed that Simpson III–IV [HR 3.01, 95% CI 1.31–6.931.03–1.24, p = 0.009] and age > 65 years [HR 2.48, 95% CI 1.20–5.13, p = 0.014] reduced PFS. The impact of postoperative RT on PFS remained statistically insignificant, even in a propensity-score matched survival analysis [n = 46; p = 0.438; OR 0.710 (0.299–1.687)]. Conclusions: In the present study, postoperative RT did not improve PFS. The most important prognostic factors remain the extent of resection and age.