Analysis of Recurrence Rates in WHO Grade 1 Meningioma’s with Elevated K_i-67 Labeling Index

Background Surgical removal of a meningioma along with its dural base and involved bone is considered the best treatment option with the lowest rate of recurrence. When this is not feasible, subtotal resection, single fraction radiosurgery, or fractionated radiation is other options. Meningiomas are graded by the World Health Organization (WHO) based on their histological characteristics. The WHO grade correlates with the tumor’s aggressiveness and risk for recurrence. The K_i-67 labeling index (K_i-67 LI) is a marker of cellular proliferation. WHO Grade I meningiomas are considered benign and generally have a K_i-67 LI <4%. The aim of this study is to analyze the effect of an elevated K_i-67 LI on the recurrence rates of WHO Grade I meningiomas.

Methods The demographics, clinical, and pathology records of all patients who underwent surgical resection of a WHO Grade I intracranial meningioma over a 12-year period (2004–2016) at our institution were reviewed. Patients were divided into three subgroups based on their K_i-67 LI: low (<4%), intermediate (5–9%), and high (>10%).

Results A total of 282 patients met the inclusion criteria—221 with low K_i-67, 47 intermediate, and 14 high. The mean age is 62 years with 203 (72%) being female. From this sample, a total of 33 patients had a recurrent episode postresection; 21 of the low K_i-67 (9.5% of all low K_i-67 patients), 8 (17.02%) of intermediate K_i-67, and 4 (28.57%) of high K_i-67. Univariate analysis demonstrated a positive correlation between increased K_i-67 LI and risk of recurrence after correcting for extent of resection. The intermediate group had 2.5 times and the high group had 3.5 times increased hazard ratio compared with the low group.

Conclusion Elevated K_i-67 LI in WHO Grade I intracranial meningiomas predicts a higher risk of recurrence. This subset of patients requires close radiographic observation to detect a recurrence that may prompt consideration for repeat surgical resection or adjuvant treatment in the form of single fraction or fractionated radiation therapy.