Outcomes After Salvage Reirradiation for Recurrent Meningioma

Re-irradiation for recurrent intracranial meningiomas: Analysis of clinical outcomes and prognostic factors

PURPOSE

Re-irradiation (re-RT) for recurrent intracranial meningiomas is hindered by the limited radiation tolerance of surrounding tissue and the risk of side effects. This study aimed at assessing outcomes, toxicities and prognostic factors in a cohort of patients with recurrent meningiomas re-treated with different RT modalities.

MATERIALS AND METHODS

A multi-institutional database from 8 Italian centers including intracranial recurrent meningioma (RM) patients who underwent re-RT with different modalities (SRS, SRT, PT, EBRT) was collected. Biologically Equivalent Dose in 2 Gy-fractions (EQD2) and Biological Effective Dose (BED) for normal tissue and tumor were estimated for each RT course (α/β = 2 for brain tissue and α/β = 4 for meningioma). Primary outcome was second progression-free survival (s-PFS). Secondary outcomes were overall survival (OS) and treatment-related toxicity. Kaplan-Meier curves and Cox regression models were used for analysis.

RESULTS

Between 2003 and 2021 181 patients (pts) were included. Median age at re-irradiation was 62 (range 20-89) and median Karnofsky Performance Status (KPS) was 90 (range 60-100). 78 pts were identified with WHO grade 1 disease, 65 pts had grade 2 disease and 10 pts had grade 3 disease. 28 pts who had no histologic sampling were grouped with grade 1 patients for further analysis. Seventy-five (41.4 %) patients received SRS, 63 (34.8 %) patients SRT, 31 (17.1 %) PT and 12 (6.7 %) EBRT. With a median follow-up of 4.6 years (interquartile range 1.7-6.8), 3-year s-PFS was 51.6 % and 3-year OS 72.5 %. At univariate analysis, SRT (HR 0.32, 95 % CI 0.19-0.55, p < 0.001), longer interval between the two courses of irradiation (HR 0.37, 95 % CI 0.21-0.67, p = 0.001), and higher tumor BED (HR 0.45 95 % CI 0.27-0.76, p = 0.003) were associated with longer s-PFS; in contrast, Ki67 > 5 % (HR 2.81, 95 % CI 1.48-5.34, p = 0.002) and WHO grade > 2 (HR 3.08, 95 % CI 1.80-5.28, p < 0.001) were negatively correlated with s-PFS. At multivariate analysis, SRT, time to re-RT and tumor BED maintained their statistically significant prognostic impact on s-PFS (HR 0.36, 95 % CI 0.21-0.64, p < 0.001; HR 0.38, 95 % CI 0.20-0.72, p = 0.003 and HR 0.31 95 % CI 0.13-0.76, p = 0.01, respectively). Acute and late adverse events (AEs) were reported in 38 (20.9 %) and 29 (16 %) patients. Larger tumor GTV (≥10 cc) was significantly associated with acute and late toxicity (p < 0.001 and p = 0.009, respectively).

CONCLUSIONS

In patients with recurrent meningiomas, reirradiation is a feasible treatment option associated with acceptable toxicity profile. Prognostic factors in the decision-making process have been identified and should be incorporated in daily practice.

Clinical Outcomes of Recurrent Intracranial Meningiomas Treated with Proton Beam Reirradiation

Purpose

Recurrent meningiomas remain therapeutically challenging, often progressive despite multimodality salvage. There are limited data guiding reirradiation (reRT), and proton beam radiation therapy (PBRT) offers a potential advantage owing to lower integral brain dose.

Patients and Methods

We retrospectively conducted a review of 16 patients who received PBRT reRT for recurrent meningiomas. Kaplan-Meier and proportional hazards were used to determine post-PBRT progression-free survival (PFS) and overall survival (OS) and to evaluate clinical predictors.

Results

At diagnosis, 7 (44%), 8 (50%), and 1 (6%) patient had World Health Organization (WHO) grade I, II and III tumors, respectively. All received prior radiation therapy (RT) to a median of 54 Gy (range 13-65.5). Median time to PBRT reRT after prior RT was 5.8 years (range 0.7-18.7). Median PBRT dose was 60 Gy(RBE) (range 30-66.6), and median planning tumor volume (PTV) was 76 cm³ (range 8-249). Median follow-up was 18.8 months. At last follow-up, 7 intracranial recurrences (44%) and 3 disease-related deaths (19%) were found. Median cohort PFS was 22.6 months, with 1- and 2-year PFS of 80% and 43%, respectively. Median OS was not achieved, with 1- and 2-year OS of 94% and 73%; all deaths were felt to be related to meningioma. Patients with initially grade I tumors had improved PFS versus higher grade (Hazard Ratio, HR = 0.23, P = .03) with 1- and 2-year PFS estimates of 100% versus 71% and 75% versus 29%, respectively. Longer interval between prior RT and PBRT also predicted improved PFS (P = .03) and OS (P = .049). Overall late grade 3+ toxicity rate was 31%. Two patients (13%) developed radionecrosis at 6 and 16 months after PBRT; only 1 was symptomatic.

Conclusions

This is the first series specifically analyzing PBRT alone as a reRT strategy for recurrent meningioma. We report fair intracranial control with low rates of radionecrosis at 1 year after reRT. However, strategies to achieve durable outcomes are needed, particularly for high-grade tumors.

Radiologic Response and Disease Control of Recurrent Intracranial Meningiomas Treated With Reirradiation

PURPOSE

To evaluate the clinical outcomes of reirradiation of recurrent meningiomas and factors related to patient selection and treatment modality.

METHODS AND MATERIALS

Recurrent meningioma patients who failed prior stereotactic radiosurgery (SRS) or fractionated external beam radiation therapy (EBRT) received reirradiation using either SRS or EBRT. Complete response (CR), partial response (PR), and progression after reirradiation were evaluated using the MacDonald criteria. Local control (LC), progression-free survival (PFS), and overall survival (OS) after reirradiation were analyzed using the Kaplan-Meier method. Logistic and Cox regression analyses were performed to identify factors associated with reirradiation modality and PFS, respectively.

RESULTS

Forty-three patients (14 grade 1/unknown, 29 grade 2/3) were reirradiated with SRS (67%) or EBRT (33%). Median time from initial SRS/EBRT to reirradiation was 60 months (range, 7.5-202); median tumor volume at the time of reirradiation was 4.8 cm³ (range, 0.14-64). After a median radiologic follow-up of 19.4 months, the response rate (CR + PR) was 8% for grade 1 and 20% for grade 2/3 meningiomas. After 2 years, LC was 78%, PFS was 63%, and OS was 80%. Larger tumor volume and prior SRS were associated with reirradiation using EBRT. Reirradiated grade 2/3 meningiomas had significantly worse PFS than grade 1 (2-year PFS: 50% vs 92%, respectively; P = .02) but not LC (P = .11) or OS (P = .39). On multivariable analysis, worse PFS was significantly associated with grade 2/3 histology (hazard ratio, 3.92; 95% confidence interval, 1.33-11.6) as well as worse Karnofsky Performance Scale score but not reirradiation dose, volume, and modality. Grades 3 to 4 radiation necrosis developed in 4 patients (10%).

CONCLUSIONS

Reirradiation of recurrent meningiomas appears to be feasible with promising clinical outcomes and an acceptable toxicity profile.