Boswellia Serrata for Cerebral Radiation Necrosis After Radiosurgery for Brain Metastases

Radiation necrosis (RN) is a dose-limiting toxicity of stereotactic radiosurgery (SRS) for brain metastases. Oral corticosteroids are not optimal for long-term management, given multiple side effects. Boswellia serrata (BS) is an over-the-counter supplement traditionally known for its anti-inflammatory properties and has recently been shown to reduce cerebral edema. We evaluated the response rates of BS in a series of patients with RN after SRS for brain metastases.

We identified patients who developed any grade RN after SRS and received BS for ≥2 months at a target dose of 4050 to 4500 mg daily. The primary endpoint was objective response rate (ORR), including complete response (CR) or partial response (PR), defined as ≥30% decrease in edema volume on T2-fluid-attenuated inversion recovery magnetic resonance imaging from baseline.

A total of 100 patients received BS, of which 94 patients with adequate follow-up were included. The median SRS dose was 24 Gy in 3 fractions, and 44%, 47%, and 9% of patients had grade 1, 2, and 3 RN, respectively. The best response was CR in 12% and PR in 48%, while 28% had stable edema and 12% had progression of edema. The overall ORR was 59.6% (95% CI, 48.9%-69.6%). ORR was 62%, 63%, and 33% for grade 1, 2, and 3 RN, respectively. The median duration of response in patients with CR or PR was 13.9 months (IQR, 9-23). Among 69 patients (73%) who never received steroids, received prior steroids only, or had a stable or decreasing steroid requirement of ≤4 mg per day of dexamethasone for at least >1 week prior to starting Boswellia, the ORR was 63.8%. Fourteen percent of patients had National Cancer Institute Common Terminology Criteria for Adverse Events grade 1, and 2% had grade 2 gastrointestinal toxicity. A total of 67% of patients remained on BS at the last follow-up.

Our study suggests that BS is a safe and feasible treatment option for grade 1 to 3 RN after SRS. Further prospective studies comparing BS with a placebo are warranted.