Background: Studies on meningioma are reported with inadequate allowance for competing causes of progression or death. The aim of this study was to describe the outcome of patients with intracranial WHO grade I meningioma and identify factors that may influence disease progression and cause-specific survival.
Methods: Pathology reports and clinical data of 505 WHO grade I meningiomas treated between January 2003 and December 2017 were retrospectively reviewed at a single institution. We estimated a cumulative incidence function for progression and cause-specific mortality. A competing risk analysis was conducted on clinical and histological criteria. Median follow-up was 6.2 years.
Results: A total of 530 surgical resections were performed on 505 cases. Forty-one patients received radiotherapy (RT). At data collection, 84 patients had died of their meningioma disease or demonstrated a recurrence eventually treated by redo surgery or RT. The risks of recurrence or meningioma-related death at 5 years were 16.2%, 95%CI[12.5, 20], whereas 5-year overall survival was 86.1%, 95%CI[82.8, 89.6]. In the multivariable Fine-Gray regression for a competing risk model, venous sinus invasion (SHR = 1.8, 95%CI[1.1, 2.9], p0.028), extent of resection (SHR = 0.2, 95%CI[0.1, 0.3], p < 0.001), and progressing meningioma (SHR = 7, 95%CI[3.3, 14.8], p < 0.001) were established as independent prognostic factors of cause-specific death or meningioma progression. In contrast, age at diagnosis < 65 years (HR = 1.1, 95%CI[1, 1.1], p < 0.001) and redo surgery for meningioma recurrence (HR = 2.6, 95%CI[1.4, 5], p = 0.00252) were predictors of the overall survival.
Conclusions: In this large series, WHO grade I meningioma treatment failure correlated with venous sinus invasion, incomplete resection, and progressing tumour; shorter survival correlated with increased age and redo surgery for recurrence. We recommend the cumulative incidence competing risk approach in WHO grade I meningioma studies where unrelated mortality may be substantial, as this approach results in more accurate estimates of disease risk and associated predictors.
Keywords: Competing risks; Outcome; Prognostic factors; Recurrence; WHO grade I meningioma.