Article
Surgical treatment of WHO grade I gliomas – implications of tumour localisation on outcome
Chirurgische Behandlung von WHO Grad I Gliomen – Bedeutung der Tumorlokalisation auf das Outcome
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Published: | June 26, 2020 |
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Objective: WHO grade I intracranial gliomas are usually referred to as benign tumors and complete surgical resection is supposed to improve outcome. Unlike other types of glioma however, WHO°I tumors often affect patients at a younger age and are preferentially located within the posterior fossa (PF) which renders surgical treatment particularly demanding. This study assessed surgical and clinical outcome in WHO°I gliomas with emphasis upon PF tumors.
Methods: We retrospectively reviewed all consecutive WHO°I glioma resections from 06/2009-12/2017 at our institution. All resections were done under 1,5 tesla intraoperative MRI guidance. Extent of resection (EOR) was assessed volumetrically under consideration of cystic/solid proportions and T1 and FLAIR lesion size. Progression free survival times (PFS, either clinically or radiologically) of supratentorial and PF tumors were compared and Kaplan-Maier and multivariate Cox regression was calculated for the variables of PFS.
Results: We identified 76 WHO°I gliomas (53 pilocytic astrocytomas, 13 gangliogliomas, 6 DNETs, 4 subependymomas) with 29 (38%) located in the PF. Median age was 16 (range 1-73), 75% of cases were <25y at the time of surgery. Compared to supratentorial lesions, PF tumors were younger (mean age 16.2±13.6y vs. 25.3±16.6y,p=0.009), more often cystic (66% vs. 38%,p=0.017), more likely to show new neurologic symptoms postoperatively (28% vs. 15% p<0.0001) as well as at the 3-month follow-up (6% vs. 2%, p<0.0001) and had more wound complications (29% vs. 6%, p=0.018), respectively. EOR was comparable according to T1w images (97% vs. 96%, p=0.58) and FLAIR images (94% vs. 94%, p=0.77). PF tumors showed significantly longer mean PFS (93.6m vs. 64.0m, p=0.006). In multivariate regression, supratentorial location (OR 51.7, 95% C.I. 4.4-606.2, p=0.002) and age <18y (OR 9.9, 95% C.I. 1.8-54.3, p=0.008) were independently associated with earlier progression. Histology, recurrent tumors or EOR were not associated with PFS.
Conclusion: We evaluated the surgical treatment of WHO°I gliomas corroborating PF resections to be more complex procedures with higher postoperative morbidity. However, we observed marked discrepancies in PFS despite a comparable EOR in favor of PF tumors. This implies that there is a probability for differences in the biologic behavior betweeen tumors in the PF and supratentorial tumors within the benign histology of these gliomas. Careful monitoring and evaluation of adjuvant treatment options might be warranted particularly in younger patients with supratentorial WHO°I gliomas.