MKI67 and meningioma: However, no predictive value was observed in Simpson grade 4 resections regardless of WHO grade.<h4>Conclusion</h4>These findings highlight that Ki-67 PI should be interpreted in the context of both WHO grade and extent of resection, and, if done so, may offer potential value to refine individualized surveillance strategies in meningioma patients with gross total resection in the initial 10-year postoperative timeframe.