Brachytherapy for Recurrent High-grade Meningiomas: An Institutional Experience

Introduction: Atypical and malignant meningiomas often recur despite initial aggressive management strategies including surgery and external beam radiation. Adjuvant radiation has been shown to improve patient outcomes in high-grade meningioma. Brachytherapy (BT) with radioactive I-125 or Cs-131 seeds placed in the resection cavity at the time of surgery is a potentially useful and targeted method of radiation treatment in these challenging cases.

Methods: With appropriate institutional review board approval, patients with atypical and malignant recurrent meningiomas treated with BT at our institution since 2002 were retrospectively reviewed. Patients were independently selected for treatment with BT as part of standard-of-care with a multi-disciplinary team discussion and decision. Case records were reviewed including all clinical, radiological, and follow-up information. Descriptive and statistical analyses were performed.

Results: Since 2002, 15 patients with recurrent high-grade meningioma were treated with repeat surgery and intraoperative BT. 8 patients were male (53%). There were 8 WHO grade II cases and 7 WHO grade III based on pathology. Lesions were located throughout the cranium, but were primarily supratentorial in the convexity and parafalcine regions. 4 out of the 15 patients had developed high-grade meningioma from malignant transformation of a previous, biopsy-confirmed grade I lesion. Prior to BT, the median number of operations was 1 in grade II cases and 2 in grade III. All patients received some form of external beam radiation therapy prior to brachytherapy.

Survival analyses demonstrated 5-year overall survival for the entire cohort at 65%. As expected, there was a statistically significant difference in 5-year survival between grade II (87.5%) and grade III (36%). After BT, 2.5-year survival was calculated at 85% for grade II lesions and 46% for grade III lesions with no statistically significant difference between subgroups.

BT is not without risk; 6 out of 15 cases (40%) required re-operation for infection or wound dehiscence. Of note, some patients had risk factors for wound complications including diabetes, active smoking history, and adjuvant chemotherapeutic treatment with bevacizumab.

Conclusions: High-grade meningiomas are challenging to manage with high recurrence rate and poor long-term survival despite aggressive surgical and radiation therapy. Although additional research is necessary, brachytherapy with intraoperative radioactive seed placement has the potential to improve local radiation delivery and ultimately survival in recurrent high-grade meningioma. In weighing the risks and benefits of BT, a multi-disciplinary team must account patient-specific wound factors such as diabetes, smoking history, prior radiation, wound condition from prior operation(s), and possible future chemotherapy adverse effects.