Long-term stroke risk of single-fraction photon-based stereotactic radiosurgery for meningioma

A recent randomized study of fractionated radiation therapy (RT) examining 44 subtotally resected/recurrent benign meningioma patients revealed that at median follow-up of 17.1 years, the risk of stroke following proton-photon RT was 20.5%; the average stroke developed 5.6 years following RT completion (Sanford et al., 2017). This stroke risk is up to 10 times higher than the 2-6% rate expected for the general population of ages 40-79 (Mozaffarian et al., 2015). The stroke rate following single-fraction stereotactic radiosurgery (SRS) has not been previously studied in meningioma patients.

A PubMed database search for relevant articles examining SRS for meningioma with minimum mean/median follow-up of six years was undertaken. Stroke rate was assessed either from direct description in manuscripts, or from extrapolating post-SRS complications from reported clinical examinations (i.e. hemiparesis/weakness, pituitary dysfunction following treatment of cavernous sinus lesions). Results were then culled to determine an overall stroke rate.

Fourteen studies met inclusion criteria; 1431 patients received photon-based SRS for meningioma with a sufficient long-term follow-up. Median/mean follow-up ranged from 75 to 144 months. Operative resection prior to SRS occurred in 769/1377 patients (55.8%) for whom surgical history was reported. Twenty-four patients suffered a stroke following SRS, yielding a rate of 1.7%.

The long-term stroke rate following single-fraction photon-based SRS for benign meningioma was 1.7%, more than twelve times lower than for fractionated proton-photon RT and comparable to that expected for the general population. The majority of patients underwent resection prior to SRS. These findings indicate that for patients with benign meningioma desiring to avoid the high stroke risk of fractionated proton-photon RT, SRS has a comparable stroke risk profile to observation. Such findings are pertinent for radiation oncology, neuro-oncology, and neurosurgery management of these patients.