Proliferation Index Correlates with Long-Term Recurrence after Complete Resection of WHO Grade-I Meningioma

Objective: Meningiomas are the most common benign intracranial tumor, and surgical resection is the most common intervention behind observation. It is unclear what duration of imaging follow-up is reasonable for WHO grade-I meningiomas. This study examined recurrence rates, timing of recurrence, and risk factors for recurrence in patients undergoing a complete resection (as defined by both postoperative MRI and intraoperative impression) of a WHO grade-I meningioma.

Methods: This was a retrospective, single-center study examining recurrence risk for adult patients with a single-intracranial meningioma that underwent complete surgical resection. Univariate and multivariate nominal logistic regression and Cox's proportional hazard analyses were performed to identify variables associated with recurrence and time to recurrence, respectively. Two supervised machine learning algorithms based on decision trees (gradient boosted decision trees [GBDT] and random forests) were then implemented to identify factors within the cohort that were associated with recurrence.

Results: The cohort consisted of 823 patients who met inclusion criteria, and 56 (6.8%) patients had recurrence on imaging follow-up. Median age of the cohort was 56, and 77.4% of patients were female. Median duration of head imaging follow-up for the entire cohort was 2.7 years but for the subgroup of patients who had a recurrence, median follow-up was 10.1 years. Estimated 1-, 5-, 10-, and 15-year recurrence-free survivals were 99.8% (95% CI: 98.8–99.9%), 91.0% (95% CI: 87.7–93.6%), 83.6% (95% CI: 78.6–87.6%), and 77.3% (95% CI: 69.7–83.4%) for the entire cohort. The minority of patients were symptomatic at recurrence (19.6%) yet the majority underwent intervention (87.5%). Recurrence for the cohort was documented from 0.93 to 20.7 years after surgery. Univariate analysis found that tumor location, tumor volume, MIB-1 index, Simpson's grade, and follow-up duration were all associated with documented recurrence. On multivariate analysis, MIB-1 (unit OR by increase of 1: 1.34, 95% CI: 1.13–1.58, p = 0.0003) and follow-up duration (unit OR by year: 1.11, 95% CI: 1.03–1.21, p = 0.012) were both associated with recurrence. Multivariate Cox's proportional hazard analysis was repeated with the continuous labeling index substituted with an MIB-1 index cut-off of 8 determined by recursive partitioning analysis, which yielded only MIB-1 ≥8 (p = 0.003) as significantly associated with recurrence (HR = 5.03, 95% CI: 1.72–14.71). For tumors with an MIB-1 index <8, recurrences were documented up to an imaging follow-up of 8 years. For tumors with an MIB-1 index ≥8, recurrences were documented up to an imaging follow-up of 12 years.

Conclusion: Long-term imaging follow-up is important even for patients considered to be at low risk of recurrence after a complete resection of a meningioma. MIB-1 labeling index may help predict patients at greater risk of recurrence. Imaging screening for at least 8 years in for patients with an MIB-1 index <8 and at least 12 years for MIB-1 index ≥8 may be needed to detect long-term recurrences.

 

Scroll to top

No conflict of interest has been declared by the author(s).

Publication History

Article published online:
15 February 2022