Low expression of Ki-67/MIB-1 labeling index in IDH wild type glioblastoma predicts prolonged survival independently by MGMT methylation status
Paolo Tini, Mariya Yavoroska, Maria Antonietta Mazzei, Clelia Miracco, Luigi Pirtoli, Miriam Tomaciello, Francesco Marampon, Giuseppe Minniti
Abstract
Abstract Purpose The Ki-67/MIB-1 labeling index (LI) is clinically used to differentiate between high and low-grade gliomas, while its prognostic value remains questionable. Glioblastoma (GBM) expressing wild-type isocitrate dehydrogenase IDH wt , a relatively common malignant brain tumor in adults, is characterized by a dismal prognosis. Herein, we have retrospectively investigated the prognostic role of Ki-67/MIB-1-LI in a large group of IDH wt GBM. Methods One hundred nineteen IDH wt GBM patients treated with surgery followed by Stupp’s protocol in our Institution between January 2016 and December 2021 were selected. A cut-off value for Ki-67/MIB-1-LI was used with minimal p-value based approach. Results A multivariate analysis showed that Ki-67/MIB-1-LI expression < 15% significantly correlated with a longer overall survival (OS), independently from the age of the patients, Karnofsky performance status scale, extent of surgery and O 6 -methylguanine (O6-MeG)-DNA methyltransferase promoter methylation status. Conclusions Among other studies focused on Ki-67/MIB-1-LI, this is the first observational study showing a positive correlation between OS of IDH wt GBM patients and Ki-67/MIB-1-LI that we propose as a new predictive marker in this subtype of GBM.