Prognostic value of Ki-67 index in primary intracranial tumors of infants

Abstract

Objective Primary intracranial tumors are rare tumors in infants. They differ from those found in other pediatric age groups in terms of clinical presentation, histopathological diagnosis, adjuvant therapies, and outcome. Ki-67 index has also shown promising results as a prognostic factor in different types of intracranial tumors in children and adults. However, the importance and the best cutoff point of Ki-67 index in primary intracranial tumors of infants remains unclear. We aimed to analyze prognostic value of Ki-67 index in primary intracranial tumors of infants. Methods This study retrospectively reviewed the records of 28 infants undergoing surgical resection for primary intracranial tumors between April 2016 and March 2021. We analyzed clinical characteristics, tumor location, extent of resection, histopathological diagnosis, Ki-67 index, and overall survival (OS). To define the most relevant cutoff value for Ki-67 index, "Cutoff Finder " was used. Results The median age at diagnosis was 188 days for all patients. Fifteen of the patients were boys and 13 were girls. Tumors were located supratentorial in 13 patients and infratentorial in 15 patients. Gross total resection was performed in 7 of 13 supratentorial tumors and 9 of 15 infratentorial tumors. The mean Ki-67 index of the supratentorial tumors was 49.6%, the median was 55%; for infratentorial tumors, the mean was 49.9%, and the median was 70%. Tumor grade (p = 0.019) and Ki-67 index (p = 0.003) were found as significant predictors of OS in log-rank testing for Kaplan-Meier survival analysis. Univariate cox regression analysis identified high Ki-67 index as prognostic factor for worse OS, with hazard ratio of 8.852 (95% CI 1.95-64.80; p = 0.0108). High Ki-67 index was found as independent prognostic factor for worse OS in multivariate cox regression analysis (HR 7.036; 95% CI 1.229-65.82; p = 0.0457). Conclusion High-grade and high Ki-67 index were associated with worse outcome. Ki-67 index did show a distinct prognostic value for OS within our cohort at a cutoff value of 72.5%.