Treatment outcomes of incidental intracranial meningiomas: Results from the IMPACT cohort.

BACKGROUND: Incidental findings such as meningioma are becoming increasingly prevalent. There is no consensus on the optimal management of these patients. The aim of this study was to examine the outcomes of patients diagnosed with an incidental meningioma who were treated with surgery or radiotherapy. METHODS: Single-center retrospective cohort study of adult patients diagnosed with an incidental intracranial meningioma (2007-2015). Outcomes recorded were post-intervention morbidity, histopathological diagnosis and treatment response. RESULTS: Out of 441 patients, 44 underwent treatment. Median age at intervention was 56.1 years (IQR 49.6-66.5); 35 female and 9 males. The main indication for imaging was headache (25.9%). Median meningioma volume was 4.55 cm(3) (IQR 1.91-8.61) and commonest location was convexity (47.7%). Six patients underwent surgery at initial diagnosis. Thirty-eight had intervention (34 surgery and 4 radiotherapy) after a median active monitoring duration of 24 months (IQR 11.8-42.0). Indications for treatment were radiological progression (n=26), symptom development (n=6), and patient preference (n=12). Pathology revealed WHO grade I meningioma in 36 patients and WHO grade II in four. The risk of postoperative surgical and medical morbidity requiring treatment was 25%. Early and late moderate adverse events limiting activities of daily living occurred in 28.6% of patients treated with radiotherapy. Recurrence rate following surgery was 2.5%. All meningiomas regressed or remained radiologically stable following radiotherapy. CONCLUSION: The morbidity following treatment of incidental intracranial meningioma is not negligible. Considering most operated tumors are WHO grade I, treatment should be reserved for those manifesting symptoms or demonstrating substantial growth on radiological surveillance.