Postoperative outcomes in CNS WHO grade 2 and 3 meningioma: a systematic review and meta-analysis

Abstract Purpose WHO grade 2 and 3 meningiomas account for approximately 20% of all meningiomas. The relatively lower incidence has resulted in limited representation of clinical outcomes in the literature, with only broad estimates of postoperative prognosis currently available. This study aimed to establish pooled incidence of recurrence and 5-year progression-free survival (PFS) and overall survival (OS) rates for grade 2 and 3 meningiomas. Methods A PRISMA-compliant systematic review was prospectively registered (PROSPERO CRD42023441009). MEDLINE, EMBASE, and the Cochrane Library were searched from inception to September 2023. Eligible studies enrolled adults (≥ 16 years) with histologically confirmed WHO grade 2 or 3 cranial meningiomas who underwent surgery with or without adjuvant radiotherapy and/or stereotactic radiosurgery. The primary outcome was pooled annual incidence of recurrence; secondary outcomes were pooled 5-year PFS and OS, estimated using random-effects models. Results Seventy-four studies met inclusion criteria (68 reporting on grade 2, 22 on grade 3 meningiomas), comprising 4,937 grade 2 and 253 grade 3 patients. The pooled annual incidence of recurrence was 6% (95% CI: 5–7%; I 2  = 86%) for grade 2 and 10% (95% CI: 7–14%; I 2  = 76%) for grade 3 meningiomas. For grade 2 meningiomas, pooled 5-year PFS and OS were 69% (95% CI: 63–75%; I 2  = 79%) and 85% (95% CI: 78–89%; I 2  = 72%), respectively. For grade 3 meningiomas, pooled 5-year PFS and OS were 18% (95% CI: 9–33%; I 2  = 55%) and 39% (95% CI: 30–50%; I 2  = 35%), respectively. Conclusion This systematic review and meta-analysis provides pooled estimates of recurrence rate, 5-year PFS, and 5-year OS for WHO grade 2 and 3 meningiomas. Interpretation is constrained by the predominantly retrospective design of included studies and considerable clinical heterogeneity across the pooled cohorts.