Adjuvant radiotherapy in grossly total resected grade II atypical meningiomas: a protective effect on recurrence?

Management of grade II atypical meningiomas (AM) remains controversial. Conflicting evidence exist on the possible protective effect of adjuvant radiotherapy (ART) on recurrence in grossly resected AMs. The aim of this meta-analysis is to evaluate the role of ART in grossly resected (Simpson grades 1-3) AMs on the recurrence and survival. Literature review was performed by the study investigators who handily queried the MEDLINE database using keywords and MeSH terms in different combinations using the Boolean operators "AND" or "OR," and database-related filters to maximize the chance to identify articles focusing on role of radiotherapy in atypical (WHO grade II) meningiomas. Data were retrieved from comparative studies of AMs undergone surgical resection alone vs. surgery + ART. Only grossly total resected AMs (Simpson grades 1-3) were included. The individual and pooled odds ratio (OR) for the crude recurrence, progression free survival (PFS) at 1, 3 and 5-years, as well as for the overall survival (OS) at 5-years were calculated by using the Mantel-Haenszel model in surgery alone vs. surgery + ART. Eleven studies were considered eligible. 8 were included for the outcome "crude recurrence;" 6 for PFS at 1-3 years, 7 for PFS at 5-years; 6 for the OS at 5-years. Results suggest that surgery + ART might have a protective role on recurrence in gross-totally resected AMs (OR:1.66). Specifically, surgery + ART slightly improved PFS at 1-year (OR:0.92) and more consistently at 3- and 5-years (OR:0.31 and 0.35 respectively) hence favoring a combined approach. Current literature on the impact of ART after gross total resection of AM are still heterogeneous and not systematically reported. The present meta-analysis suggests a possible protective role of postoperative RT against long-term recurrence as compared to surgical resection alone.