Impact of extent of resection and adjuvant radiation therapy in the progression free survival in patients with spheno-orbital meningioma.

Background: Spheno-orbital meningiomas (SOM) are known to invaded critical skull base areas. The authors report a series of WHO I SOM, propose a subclassification of this tumor according to its extension to critical positions and analyze the impact of extent of resection and the role of stereotactic radiotherapy in tumor recurrence.

Methods: A prospective maintained university medical center registry was utilized to undertake a retrospective review of patients operated with WHO I SOM. Details related to critical skull base region's extension (superior orbital fissure, cavernous sinus, orbital apex), extent of resection and adjuvant radiosurgery were collected. Statistical calculations were preformed using IBM SPSS Statistics version 25. A p value < 0.05 was considered significant. Survival analysis was performed using Kaplan-Meier survival analysis and the log rank test.

Results: A total of 77 patients operated from 2002 to 2021 were included. There were 65 women (84.4 %) and 12 men (15.6 %). Mean age at surgery was 54.8 years (median 53 years, range 23 - 88). Tumors were defined as local in 28 (35.4 %) and with extension into the skull base critical structures in 51 (64.6 %). GTR was achieved in 35 (44.3 %), STR in 40 (50.6 %), and PR in four (5.1 %). Surgical morbidity was 10 %. There was no surgical mortality. 28 patients with STR or PR were treated with adjuvant radiotherapy. The total length of follow up was a mean of 172.3 months. There were 14 recurrences/progressive growth (17.7 %), 63 patients (79.7 %) had no recurrence/progressive growth, and two patients (2.5 %) were lost to follow-up. PFS was significant statistically different in patients with invasive tumors in whom the extent of resection was subtotal, with a longer PFS in patients that were treated with adjuvant radiotherapy. (P value < 0.001).

Conclusions: SOM could be divided in two groups according to its skull base extension facilitating decision management and outcome prediction. Patients with local WHO I SOM had higher rate of GTR and better PFS than tumors extending to involve critical regions. When STR or PR is achieved postoperative adjuvant radiotherapy is advised if there is evidence of previous tumor growth.