Original ArticleIntracranial Meningiomas: A Systematic Analysis of Prognostic Factors for Recurrence in a Large Single Institution Surgical Series
Introduction
Meningioma is the most common primary intracranial tumor, accounting for 15%–30% of primary brain tumors. According to World Health Organization (WHO) classification, about 80% are benign slow-growing meningiomas defined as grade I, associated with a low risk of recurrence after resection (∼ 10% at 5 years), 20% are atypical grade II meningiomas characterized by an intermediate clinical behavior, with a recurrence rate of 30%–40%, and <5% are anaplastic, aggressive, grade III meningiomas with a recurrence rate of 50%–80%.1, 2, 3 As recently highlighted by the European association of neuro-oncology guidelines, surgical resection is the first choice of treatment and should aim to achieve Simpson grade I resection.4 The amount of surgical resection, as defined by Simpson criteria, represents a crucial factor influencing the risk of recurrence.5 In case of Simpson grade I-II the 5-year local control rate accounts for 88%–95% in case of WHO grade I meningiomas and 60%–80% in case of WHO grade II. Conversely, for Simpson grade III-IV, the rate of local control is 50% on average.6, 7, 8 Therefore, most tumors are in favorable locations (convexity meningiomas and easily accessible skull-base meningiomas) in patients with WHO grade I. These tumors can be cured by surgery alone. WHO grade II meningioma implies an increased risk of recurrence after surgery alone, and an adjuvant treatment should be considered. The role of adjuvant radiotherapy (RT) is still unclear, particularly regarding the optimal timing and fractionation. Retrospective series on adjuvant radiotherapy after gross total resection led to different results, and prospective data are missing.4, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27 In a recent retrospective case study of 45 patients with atypical meningioma, Endo et al28 showed no additional benefit of adjuvant radiotherapy in terms of long-term tumor control. In contrast, Lee et al29 described a partial improvement of progression-free survival (PFS) in patients with subtotal resection and adjuvant radiotherapy. The ROAM/EORTC 1308 trial (ISRCTN71502099) is recruiting patients with newly diagnosed atypical meningioma (WHO grade II) who have undergone resection (Simpson grade I–III) and will be randomly assigned to either early adjuvant radiotherapy (60 Gy in 30 fractions) or observation with the aim to investigate whether RT reduces or delays the risk of tumor recurrence.30 At present, consolidate evidence about the optimal therapeutic strategy is lacking. Based on this background we systematically analyzed the outcome of a large cohort of patients with WHO grade I and II intracranial meningioma who were consecutively treated in our institution. In the present study we evaluated prognostic factors influencing the local recurrence rate, with the aim of suggesting the most adequate treatment.
Section snippets
Patients
The present study includes patients with newly diagnosed WHO grade I and II meningiomas, who underwent surgical resection at our institution. Patients with a diagnosis of neurofibromatosis type 2, WHO grade III meningioma, who underwent >1 surgical treatment or spinal location were excluded. All patients were treated in accordance with the principles of the Helsinki Declaration. This study was based on a retrospective analysis of treatment charts and received approval from the local Ethical
Patients, Treatments and Outcome
From January 2000 to December 2015, 296 patients with grade I and II meningiomas, who underwent surgical resection, were included in this analysis. Most were women (65.9%), with a Karnofsky performance status ≥80 (94.6%), grade I meningioma (79.4%), and symptomatic at diagnosis (91.5%). Among 296 patients treated, 124 (42%) had GTR and 172 (58%) had STR. Adjuvant RT at diagnosis was performed in 30 (10%) patients, 25 underwent STR, and 5 GTR (all grade II). In addition, RT was delivered to 64
Discussion
The 2016 WHO classification of central nervous system tumors defined 3 histologic subtypes for meningioma in relation to brain invasion, a mitotic count, spontaneous necrosis, sheeting, prominent nucleoli, high cellularity and small cells, as follows: “meningioma grade I” characterized by a low mitotic rate, <4/10 high-power fields (HPFs), and absence of brain invasion; “ meningioma grade II or atypical meningioma” defined by a mitotic rate 4/19 per HPF, or brain invasion, or 3 of 5 specific
Conclusion
Overall, our findings suggest that recurrence rates are variable and complicated by the heterogeneity of study populations. As expected, WHO grade II meningiomas generally have a higher recurrence rate than WHO grade I. Concerning treatments approach our data underline the value of the EOR and of adjuvant RT at diagnosis for incompletely resected meningiomas, regardless of tumor grade.
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Histological Structure of the Major Dural Sinus Walls in the Posterior Cranial Fossa: A Factor that Might Matter in Dural Sinus Surgery
2019, World NeurosurgeryCitation Excerpt :Dissection of such lesions off DS walls needs to be done with particular care, because some of the walls might be indisputably more fragile and thus at greater risk for DS injury, with subsequent severe bleeding or impaired blood flow through the sinuses. The incorporation of such in-depth knowledge of the DS into clinical practice might have a positive impact on decision making regarding the extent of tumor resection as a crucial factor influencing recurrence rate17 vs. the risk of DS injury. An unresolved ambiguity of the possible different meningeal histogenesis of the CS and TS compared with the SS and JB3-5 stems from the fact that meningeal layers covering the telencephalon arise from neural crest cells, whereas those around the brainstem derive from the cephalic mesoderm.3-5
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Conflict of interest statement: The authors declare that the article content was composed in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.