Outcomes with IMRT versus SRS Salvage Radiotherapy for Recurrent High-Grade Meningioma

Introduction: The standard treatment for accessible World Health Organization (WHO) grade II and III meningiomas is surgical resection. Unfortunately, even after gross-total resection, recurrence rates in high-grade (HG) meningiomas can range from 9 to 32%. Intensity-modulated radiotherapy (IMRT) and stereotactic radiosurgery (SRS) are mainstay therapeutic modalities used to treat recurrent high-grade meningioma after surgical resection. The role of radiotherapy (RT) modality, in particular IMRT versus SRS, on survival outcomes in patients with recurrent high-grade meningiomas is not well-established. In the present study, we compare progression-free survival in patients undergoing salvage IMRT and SRS for recurrent HG meningiomas.

Methods: A retrospective review was performed to identify all patients undergoing radiotherapy for recurrent WHO grade II and III meningiomas between 1996 and 2019 at our institution. Patients for whom adequate treatment data was unavailable or who had not previously undergone surgical resection were excluded. Predictors of survival were analyzed using multivariate Cox proportional hazards model. Kaplan–Meier survival analysis was used to assess progression-free survival in IMRT and SRS treatment groups. A p-value of <0.05 was considered statistically significant ([Tables 1] and [2]).

Results: A total of 67 cases were identified and included in the study. The median radiation doses for IMRT and SRS were 59.4 Gy (range, 16–60 Gy) and 15 Gy (range, 12–30 Gy), respectively. Two patients received fractioned SRS (25 Gy/5 fx and 30 Gy/5 fx). Median IMRT fractions were 30.5 fractions (26–33 fractions). There was no significant difference in tumor location and previous brain radiation therapy between SRS and IMRT (p = 0.44, p = 1). In a multivariate Cox’s regression model, age at radiation (HR = 1.19, p < .001) and male sex (HR = 20.32, p = 0.008) were found to be independent predictors of mortality. Kaplan–Meier survival analysis and Cox’s proportional hazards model found no significant difference in progression-free survival between patients treated with SRS versus IMRT for recurrent HG meningiomas (HR = 1.06; 0.47–2.41; [Fig. 1]).

Conclusion: Our study suggests that irrespective of tumor location, there is no significant difference in progression-free survival between SRS and IMRT in patients undergoing salvage radiotherapy for recurrent high-grade meningiomas.

Table 1 Demographic of IMRT and SRS treatment groups

Baseline demographics
	IMRT	SRS	p-Value
n	19	48
Age (SD)	62.6 (15.65)	60.1 (10.43)	0.446
Baseline KPS (SD)	85.00 (9.72)	87.18 (8.87)	0.5
Male (%)	10 (52.6)	19 (39.6)	0.485
Caucasian (%)	16 (84.2)	35 (72.9)	0.51
African American (%)	3 (15.8)	13 (27.1)	0.51

Table 2 Parameters of IMRT and SRS treatment groups

Tumor and treatment parameters
	IMRT	SRS	p-Value
WHO grade II	19 (100)	43 (89.6)	0.344
WHO grade III	0 (0)	5 (10.4)	0.344
Chemotherapy received (%)	3 (15.8)	8 (17.8)	1
Previous radiation therapy (%)	5 (26.3)	14 (29.2)	1

Fig. 1 (A, B) Progression-free survival between patients treated with SRS versus IMRT.